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An Atlas of Sphagnum-Dwelling Testate Amoebae in Bulgaria
expand article infoMilcho Todorov, Nikola Bankov
‡ Institute of Biodiversity and Ecosystem Research (BAS), Sofia, Bulgaria
Open Access

Dedicated to Neli and Deni

Introduction

Testate amoebae is a term used to unite those free-living, unicellular eukaryotes which ameboid cell is covered by an extracellular shell (test), mostly with a single main opening, and which extrude lobose or filose pseudopodia. Testate amoebae are traditionally divided into two main groups based on the morphology of pseudopodia – Arcellinida (with lobose pseudopodia) and Euglyphida (with filose pseudopodia) (Meisterfeld 2002a,b). The progress in the molecular phylogeny and phylogenomics, as a result of accumulation of much new DNA data over the last decade, have led to major revisions in the classification of most groups of organisms, including testate amoebae. Currently, it is known that testate amoebae are a polyphyletic assemblage of at least three major, unrelated taxonomic groups of unicellular eukaryotes: Amoebozoa, Stramenopiles and Cercozoa (Adl et al. 2012, 2019).

Testate amoebae are worldwide distributed and occur from the tropics to polar regions. They are present in most terrestrial and freshwater environments, as well as in brackish and marine habitats, but are especially abundant and diverse in the Sphagnum mosses. The studies on this group have significantly increased over the past two decades due to their increasing use in different applied aspects. Testate amoebae are a good model for taxonomy and evolutionary studies because of their abundance, diversity and presence of a shell, which is a reliable taxonomic feature used in diagnostic of the species. They are considered as valuable bioindicators for ecological and environmental monitoring studies, in particular, as proxies for hydrological changes, and therefore, for paleoclimate reconstruction in peatlands (Charman and Warner 1997, Mitchell et al. 2000, Booth 2002, 2007, Lamentowicz and Mitchell 2005, Qin et al. 2013, Payne et al. 2016). The fact that different species have distinct ecological requirements and after death of the amoebae their shells remain well preserved in peat and sediment makes them excellent microfossils and extremely valuable in micro-paleontological studies for palaeoenvironmental reconstructions (Tolonen 1986, Charman et al. 1998, 2001, Charman 2001, Mitchell et al. 2008, Swindles et al. 2009, 2015). Testate amoebae are very sensitive and quickly respond to environmental changes, such as water table depth, dryness, atmospheric pollution, deforestation and other human activities, and this makes them valuable biomonitors for current environmental health (Booth 2007, Nguyen-Viet et al. 2007, Payne et al. 2012, Nasser et al. 2016). Also, it has been shown that testate amoebae play an important role in the cycling of carbon, nitrogen and silica in terrestrial ecosystems (Schröter et al. 2003, Aoki et al. 2007, Jassey et al. 2015).

The studies on the Sphagnum-dwelling testate amoebae in Bulgaria started in the beginning of the 20th century, when Pateff (1924, 1928) published his works on freshwater Rhizopoda in this country. He recorded a total of 118 rhizopods, of which 52 testate amoebae from the Sphagnum mosses in the Rila, Rhodopes and Vitosha Mountains. Later, Valkanov (1932, 1934) published results of his studies on the fauna of the alpine lakes in the Rila and Pirin Mountains, and recorded many testate amoebae, which are typical inhabitants of the peat mosses. Unfortunately, no distinction was made between the species found in the lakes and in the Sphagnum mosses along the shores of the lakes. In the 1960s and 1970s several reports on the testate amoebae in the Vitosha, Rhodopes and Pirin Mountains were published (Golemansky 1965, 1966, 1968, 1974), including a lot of data on the Sphagnum-dwelling testate amoebae. In the end of the 20th and beginning of the 21th century, the number of publications concerning various aspects of taxonomy, systematics, morphology and ecology of the sphagnicolous testate amoebae in Bulgaria increased considerably (Golemansky and Todorov 1985, 1990, 1993, 2006, Todorov 1993, 2004, 2005, 2010, Todorov and Golemansky 1995, 2000, Golemansky et al. 2006, Todorov et al. 2009, 2010, 2018, Heger et al. 2010, Kosakyan et al. 2012, Bankov et al. 2018).

The aim of this atlas is to present summarised information and to illustrate comprehensively the shell morphology and structure of the majority of recorded Sphagnum-dwelling testate amoebae in Bulgaria. Since most of these species appear to be widely distributed in Europe, as well as in many other regions of the world, the atlas may be of interest to all researchers on testate amoebae and can also be used by specialists in ecology, hydrobiology, palaeoecology and environmental monitoring.

Shell morphology

Shells are the main taxonomic feature of testate amoebae and they are extremely diverse in shape, size and composition. Bonnet (1975) classified testate amoebae into sixteen morphological types according to the shape and symmetry of their shells and structure of the aperture (Fig. 1). It was shown that different morphological types are closely related to the nature of habitats and that different types can be used as indicators in ecological studies or to suggest phylogenetic relationships (Chardez 1967, Bonnet 1975, Chardez and Lambert 1981). For example, in aquatic habitats and wet mosses predominate species with a terminal and comparatively large aperture of the arcella (ARC - Arcella), acrostomic (ACS - Difflugia, ACA - Cyphoderia) and trachelostomic (TRAS - Cucurbitella, TRAA - Lesquereusia) morphological types. In habitats where the amoebae are subject to frequent droughts, e. g. aerophilic and epiphytic mosses and soils, the aperture is reduced to a slit-like opening (ACC – Assulina, Heleopera), is covered by an anterior visor or lip (PLS – Centropyxis plagiostoma, PLV – Centropyxis aerophila, CRS – Geoplagiopyxis, CRV – Plagiopyxis callida) or is highly modified, complex structure of the propylostomic (PRO – Lamtopyxis) and diplostomic (DIP – Distomatopyxis) morphological types. Finally, inhabitants of the coastal marine interstitial are adapted to the specific conditions in this environment, they have shells of the cotylostomic type (COT – Psammonobiotidae), with an enlarged collar around the aperture, used for fixation and stabilisation of the shell in the continuous tides and outflow of the water.

Figure 1.

Morphological types of testate amoebae shells: ARC – arcella; ACS – simple acrostomy; ACC – compressed acrostomy; ACA arched acrostomy; TRAS – simple trachelostomy; TRAA – arched trachelostomy; COT – cotylostomy; AXI – axial; AMP – amphystomy; ELL – ellipsostomy; PRO – propylostomy; DIP – diplostomy; PLS – simple plagiostomy; PLV – plagiostomy with visor; CRS – simple cryptostomy; CRV – cryptostomy with visor (After Bonnet, 1975).

According to the shell composition, there are four main types of shells: proteinaceous, agglutinate, siliceous and calcareous (Ogden and Hedley 1980, Meisterfeld 2002a).

Proteinaceous shells can be divided into three types: 1) shells in which the wall is more or less a flexible membrane (Microcoryciidae); 2) shells with a smooth and rigid homogeneous coat composed of mucoprotein (Hyalosphenia); 3) shells, constructed of numerous regularly arranged, hollow building units or alveoli (Arcellidae) (Fig. 2).

Agglutinate shells may be divided into two types. The shells of the first type have either a structured or sheet-like organic cement matrix in which foreign material from the environment (xenosomes), such as quartz grains or diatom frustules, is incorporated (most of Difflugiidae). It is noteworthy that the structure of the organic cement has valuable importance for the taxonomy and distinction of the species in this group. The second type of agglutinate shells is characteristic for most representatives of the families Hyalospheniidae and Heleoperidae. Their shells are composed of siliceous shell-plates with different shape and size, embedded in a sheet-like organic cement matrix. It is important to note that the species with such shells do not make their own shell-plates but obtain them by predation mainly on small euglyphids (Fig. 3).

Figure 2.

Testate amoebae with proteinaceous shells: (A, B) Hyalosphenia papilio – shell composed of mucoprotein; (C, D) Arcella gibbosa – shell composed of numerous hollow building units (alveoli).

Figure 3.

Testate amoebae with agglutinate shells: (A-D) shells composed of foreign material from the environment (xenosomes); (A, B) Difflugia oblonga; (C, D) Pontigulasia rhumbleri; (E-H) shells composed of siliceous shell-plates with different shape and size, obtained by predation mainly on small euglyphids; (E, F) Gibbocarina galeata; (G, H) Heleopera sylvatica.

Siliceous shells are composed of endogenous siliceous shell-plates (idiosomes) which are produced by the amoebae themselves. These structural elements are formed and stored in the parent’s cytoplasm prior to cell division, and are used in the division process to construct the daughter shell, identical to the parent. The shape, size and arrangement of the siliceous shell-plates (idiosomes) are species specific and have valuable taxonomic significance. The idiosomes are too different in shape and vary from oval or circular in the euglyphids (Euglyphida), through rods in Lesquereusia, and nail-like in Netzelia to quadrangular in Quadrulella (Fig. 4).

Fig. 4 . Testate amoebae with siliceous shells composed of self-produced siliceous shell-plates (idiosomes): (A, B) Euglypha tuberculata; (C, D) Lesquereusia epistomium; (E, F) Quadrulella longicollis; (G, H) Netzelia oviformis.

Calcareous shells are the least presented and are characteristic to only two genera Paraquadrula and Cryptodifflugia. The first one has quadrangular calcite shell-plates embedded in a sheet-like organic cement matrix. The second has a smooth shell surface and the wall is composed of two layers, a thin organic outer layer and a thick inner layer of amorphous calcium phosphate (Hedley et al. 1977).

Cytoplasm

Some species of testate amoebae are described only on the basis of empty shells and their biology is totally unknown. Most of the species with agglutinate shells, composed of quartz grains (xenosomes), have poorly studied cell morphology because their shells are opaque and robust, with thick walls, which prevent the study of the cytoplasm by light and transmission electron microscopy. Thus, much of our knowledge on the cell structure of testate amoebae is mainly due to the studies of species with proteinaceous, siliceous or calcareous shells (Charret 1964, Hedley and Ogden 1973, 1974, Hedley et al. 1974, 1977, Netzel 1975, 1983, Harrison et al. 1976, Bonnet et al. 1981, Golemansky et al. 1987, Ogden and Coûteaux 1987, Anderson 1990, Ogden 1991).

In general, the cell of testate amoebae is surrounded by a thin and elastic plasmalemma with numerous microtubules and microfilaments, lying beneath it and having function of a cytoskeletal structure. The cytoplasm is usually divided into two zones. The anterior zone is a granular cytoplasm and includes many food and digestive vacuoles, numerous mitochondria and peripherally located vesicles containing organic cement. The posterior zone is a dense cytoplasm, which contains nucleus, surrounded by a compact mass of granular endoplasmic reticulum, numerous ribosomes, one or more Golgi complexes, as well as several contractile vacuoles located laterally of the nucleus, close to the plasmalemma (Ogden and Hedley 1980, Meisterfeld 2002a). Most species have one nucleus and rarely the nuclei are two (many Arcella species), about ten to twenty (Arcella polypora), up to several tens or hundreds (Arcella megastoma, Difflugia urceolata, Phryganella nidulus, etc.). The nuclei of testate amoebae are two main types, according to the classification of Raikov (1982): vesicular nuclei with one large, central nucleolus and ovular nuclei with several to many small nucleoli (Fig. 5). In the smaller euglyphids (e.g. Corythion, Euglypha, Sphenoderia, Trinema) the cytoplasm usually fills the whole shell, while in larger species (Hyalospheniidae, Difflugiidae) it fills about a half or two-third of the shell and the cell is attached to the posterior part of the shell wall with numerous thin cytoplasmic strands (epipodes) (Fig. 6).

Figure 5.

Nuclei of testate amoebae: (A, B) vesicular nuclei of Arcella discoides (A) and Trinema galeata (B); (C, D) ovular nuclei of Nebela collaris (C) and Tracheleuglypha dentata (D) (large arrows – nucleus, small arrows – nucleolus).

Figure 6.

Thin cytoplasmic strands (epipodes) attaching the cell to the shell wall: (A) Arcella discoides; (B) Gibbocarina galeata; (C) Longinebela tubulosa; (D) Hyalosphenia papilio.

Pseudopodia

The movement of testate amoebae is accomplished by a steady flow of the cytoplasm, which involves the extension and retraction of pseudopodia through the shell aperture (pseudostome) and creep on the substrate. The pseudopodia have different shape and mode of activity and for a long time they have been used as a main feature in the classification of testate amoebae. There are three main types of pseudopodia: endolobopodia, ectolobopodia (reticulo-lobopodia) and filopodia. The endolobopodia are thick, digitate and granular pseudopodia with rounded ends, characteristic for most species of the order Arcellinida (suborders Sphaerothecina and Difflugina). The ectolobopodia (reticulo-lobopodia) are completely hyaline, conical, pointed, sometimes branched and may anastomose. They are presented in the suborder Phryganellina (Cryptodifflugia, Meisterfeldia, Phryganella, Wailesella). The filopodia are hyaline, filamentous, thin, straight, finely pointed, sometimes branched and are presented in all the Euglyphida (Fig. 7).

Figure 7.

Pseudopodia of testate amoebae: (A, B) endolobopodia of Lesquereusia gibbosa (A) and Heleopera sylvatica (B); (C, D) filopodia of Cyphoderia ampulla (C) and Trinema galeata (D).

Reproduction

Testate amoebae normally reproduce by binary fission, with a replication of the parent. Firstly, an identical daughter-cell is constructed and after that the fission takes place usually as a closed ortomitosis (Ogden 1979, Ogden and Coûteaux 1987, Raikov and Mignot 1991) (Fig. 8). The doubling time of the amoebae is between two and twelve days depending on the species and environmental conditions, usually shorter in a laboratory than in natural conditions (Heal 1964, Hedley and Ogden 1974, Hedley et al. 1974, 1977, Ogden 1989). It was believed for a long time that testate amoebae are reproduced only asexually. In the late 19th and early 20th century the reports in which are provided evidence for the presence of sexuality in testate amoebae are scarce (Jickeli 1884, Blochmann 1887, Penard 1902, Awerintzew 1906, Reukauf 1912, Dunkerly 1923, Dangeard 1900). Later, Valkanov (1962, 1966) studied in detail the reproduction in testate amoebae and distinguished four types of copulation: 1) type Difflugia in which the cytoplasm of one individual passes entirely into the shell of the other individual, where the two cells merge and form a zigocyst (sexual cyst) – widely distributed in the genera Centropyxis, Difflugia, Lesquereusia, Nebela, Pontigulasia, Sphenoderia, Trinema, etc.); 2) type Pyxidicula in which two individuals merge and form a zigocyst in the space between the two shells – in Pyxidicula and Phryganella; 3) type Euglypha, where the cytoplasm of the copulated individuals goes out of the shells, merge and compose a new larger shell, in which the zigocyst remains – in Assulina, Euglypha, Valkanovia, etc.; 4) type Clypeolina which is the most specific and occurs only in Clypeolina, which shell is composed of two valves. The individuals in copulation touch laterally, the inner valves of each of them disintegrate, the cells merge and form the zygocyst, which is covered by a shell, composed of the outer valves of the copulated individuals. Lüftenegger and Foissner (1991) established the presence of plasmogamy and karyogamy with subsequent cyst formation in Paraquadrula. Mignot and Raikov (1992) provided new evidence for the meiosis in testate amoebae, studying in details the meiosis and autogamy in the cyst of Arcella. Iudina and Sukhanova (2000) studied the cytoplasmic fusion and karyogamy in Corythion delamarei and documented division of the synkaryon into four nuclei and formation of four daughter cells as a result of meiosis. Currently, there is clear evidence that testate amoebae, as well as many other microbial eukaryotes, can reproduce also sexually (Lahr et al. 2011, Tekle et al. 2017, Hofstatter et al. 2018).

Figure 8.

Reproduction of testate amoebae by binary fission: (A) Sphenoderia lenta; (B) Heleopera sylvatica; (D) Arcella dentata (the shell of parent is dark-brown because the alveoli are enriched with iron, used to strengthen the shell wall; this inorganic material is not usually present in the alveoli of young animals and their shells are light yellowish).

Cysts

Besides the reproductive cysts testate amoebae can produce resistant and short-time cysts as a protection against unfavorable conditions in the environment, such as drought, extremal temperatures, lack of food or anaerobiosis. Usually, the resistant cysts are formed within the shell and are contained within a thick organic membrane. During encystment the amoebae reduce the volume of cytoplasm and number of organelles, and in such encysted state they can survive for a long time (several months). In the period of desiccation, many soil- and moss-dwelling species form short-time cysts (precists), which differ from the resistant cysts by their relatively thin membrane enclosing the cell and by their ability to pass quickly into active life when appropriate conditions in the environment occur. Often, testate amoebae forming cysts additionally seal the shell aperture with a plug of siliceous or extraneous particles (Fig. 9).

Figure 9.

Cysts of testate amoebae: (A, B) short-time cysts of Heleopera rosea (A) and Hyalosphenia papilio (B); (C) resistant cyst of Nebela collaris and additional sealing of the shell aperture with a plug of siliceous and extraneous particles.

Feeding

Testate amoebae are mostly phagotrophic organisms feeding on bacteria, algae and fungi, thus playing an important role in nutrient recycling in the aquatic and terrestrial ecosystems. Some larger species (mostly Hyalospheniidae) are predators preying on other Protozoa, such as the euglyphid testate amoebae and naked amoebae, or small metazoan organisms, such as the nematodes and rotifers (Yeates and Foissner 1995, Ogden 1989, Gilbert et al. 2000, Han et al. 2008). At the same time, testate amoebae can be preyed on by nematodes, earthworms, collembolans and mites, thus re-entering the classical food chain (Bamforth and Lousier 1995, Wilkinson and Mitchell 2010). Significantly less are the mixotrophic testate amoebae, which are capable of building a symbiotic relationship with the phototrophic algae (zoochlorellae) and combine both phagotrophy and phototrophy (e.g. Amphitrema, Archerella, Difflugia and Hyalosphenia) (Fig. 10). The host heterotrophic species usually supply their symbiotic algal cells with nitrogen and CO2, and in turn, the algae supply their hosts with photosynthetic products, such as maltose and oxygen (Esteban et al. 2010, Summerer et al. 2007). In some Difflugia species this symbiotic relationship can be facultative and the host can shift to heterotrophic nutrition if exposed to prolonged darkness or if the environment lacks symbionts. Most frequently, the symbiotic relationship is obligatory and the host can no longer survive without its symbionts. Schönborn (1965) showed experimentally that Archerella flavum and Hyalosphenia papilio can not survive for long periods in the dark. His study also demonstrated that A. flavum depends entirely on the symbiotic algae for its nutrition requirements, while H. papilio provides up to 40% of the required nutrients from photosynthetic products of the algae and the rest through phagotrophy.

Figure 10.

Symbiotic relationship of testate amoebae with phototrophic algae (zoochlorellae): (A) Archerella flavum; (B) Hyalosphenia papilio.

Materials and Methods

The presented data on species diversity and distribution of the Sphagnum-dwelling testate amoebae were based on the review of all available literature from Bulgaria. In addition, we included unpublished data from our studies in the period 2016 – 2018.

The material for the present study was extracted from wet Sphagnum mosses, collected at the mountains Western Stara Planina, Rhodopes, Vitosha, Rila and Pirin. A total of 126 samples of testate amoebae from 23 localities were collected and examined. Testate amoebae were extracted from fresh Sphagnum mosses at the sampling site and concentrated by sieving (350 μm). The resulting fraction (50 ml) was observed with optical microscope “Amplival” (Zeiss-Jena) using 40x objective and 10x oculars lens. The light micrographs (LM) were taken using an Axio Imager M2-Carl Zeiss compound microscope with a digital camera (ProgRes C7) and specialised software (CapturePro Software 2.8). Most of the pictures for illustration of the pseudopodia and nuclei of the live individuals were taken with differential interference contrast (DIC).

The morphometric characterisation of the species was made using our own measurements of individuals isolated from the wet Sphagnum mosses, collected during this study. The following basic characters were measured: arithmetic mean; median (M); standard deviation (SD); standard error of mean (SE); coefficient of variation in % (CV); and extreme values (Min and Max). The statistical analysis was performed using the STATISTICA Software, Version 10.0 (StatSoft 2010).

For the scanning electron microscopy (SEM) the specimens were isolated by searching through small isolates of material in a petri dish. The specimens were extracted using a glass micropipette, washed several times in distilled water, and then individual shells were positioned with a single-hair brush on a previously mounted double-sided adhesive tape on a standard aluminium stub and air-dried. The shells were coated evenly with gold in a vacuum coating unit. The photomicrographs were obtained using scanning electron microscopes JEOL JSM-5510 and LYRA/TESCAN 5007, operating at 10 kV.

Classification

The classification of testate amoebae at higher ranks follows Adl et al. (2019). Taxonomic revision of some genera and families, as well as numerous taxonomic and nomenclature changes, based on recent molecular studies and subsequent phylogenetic reconstructions, have also been taken into account (Lara et al. 2007, Mazei and Warren 2012, 2014, 2015, Kosakyan et al. 2012, 2016a, 2016b, Chatelain et al. 2013, Gomaa et al. 2013, 2017, Lahr et al. 2013, 2019, Bobrov 2016, Blandenier et al. 2017, Dumack et al. 2017, Duckert et al. 2018).

Eukaryotes

Domain Amorphea Adl et al., 2012

Supergroup Amoebozoa Lühe, 1913, sensu Cavalier-Smith, 1998

Phylum Tubulinea Smirnov et al., 2005

Class Corycida Kang et al., 2017

Genus Amphizonella Greeff, 1866

Genus Diplochlamys Greeff, 1888

Class Elardia Kang et al., 2017

Order Arcellinida Kent, 1880

Suborder Glutinoconcha Lahr et al. 2019

Infraorder Sphaerothecina Kosakyan et al., 2016

Family Arcellidae Ehrenberg, 1843

Genus Antarcella Deflandre, 1928

Genus Arcella Ehrenberg, 1830

Family Netzeliidae Kosakyan et al., 2016

Genus Cyclopyxis Deflandre, 1929

Genus Netzelia Ogden, 1979

Incertae sedis Sphaerothecina, Genera: Cornuapyxis Coûteaux et Chardez, 1981; Cucurbitella Penard, 1902; Distomatopyxis Bonnet, 1964; Ellipsopyxella Bonnet, 1975; Ellipsopyxis Bonnet, 1965; Geopyxella Bonnet et Thomas, 1955; Lamtopyxis Bonnet, 1974; Protocucurbitella Gauthier-Lièvre et Thomas, 1960; Suiadifflugia Green, 1975; Trigonopyxis Penard, 1912.

Infraorder Longithecina Lahr et al., 2019

Family Difflugiidae Wallich, 1864

Genus Difflugia Leclerc, 1815

Genus Pseudonebela Gauthier-Lièvre, 1953

Family Lesquereusiidae Jung, 1942

Genus Lesquereusia Schlumberger, 1845

Genus Microquadrula Golemansky, 1968

Genus Paraquadrula Deflandre, 1932

Genus Pomoriella Golemansky, 1970

Infraorder Excentrostoma Lahr et al., 2019

Family Centropyxidae Jung, 1942

Genus Centropyxis Stein, 1857

Genus Proplagiopyxis Schönborn, 1964

Family Plagiopyxidae Bonnet et Thomas, 1960

Genus Bullinularia (Penard, 1907) Deflandre, 1953

Genus Geoplagiopyxis Chardez,1961

Genus Hoogenraadia Gauthier-Lièvre et Thomas, 1958

Genus Paracentropyxis Bonnet, 1960

Genus Plagiopyxis Penard, 1910

Genus Planhoogenraadia Bonnet, 1977

Genus Protoplagiopyxis Bonnet, 1962

Incertae sedis Excentrostoma, Genera: Conicocassis Nasser and Patterson, 2015; Oopyxis Jung, 1942.

Infraorder Hyalospheniformes Lahr et al., 2019

Family Hyalospheniidae Schultze, 1977, emend. Kosakyan and Lara, 2012

Genus Alabasta Duckert et al., 2018

Genus Alocodera Jung, 1942

Genus Apodera Loeblich and Tappan, 1961

Genus Certesella Loeblich and Tappan,1961

Genus Cornutheca Kosakyan et al., 2016

Genus Gibbocarina Kosakyan et al., 2016

Genus Hyalosphenia Stein, 1859

Genus Longinebela Kosakyan et al., 2016

Genus Mrabella Kosakyan et al., 2016

Genus Nebela Leidy, 1874

Genus Padaungiella Lara and Todorov, 2012

Genus Planocarina Kosakyan et al., 2016

Genus Porosia Jung, 1942

Genus Quadrulella Cockerell, 1909

Infraorder Volnustoma Lahr et al., 2019

Family Heleoperidae Jung, 1942

Genus Heleopera Leidy, 1879

Suborder Organoconcha Lahr et al., 2019

Family Microchlamyidae Ogden, 1985

Genus Microchlamys Cockerell, 1911

Genus Spumochlamys Kudryavtsev and Hausmann, 2007

Genus Pyxidicula Ehrenberg, 1838

Suborder Phryganellina Bovee, 1985

Family Phryganellidae Jung, 1942

Genus Phryganella Penard, 1902

Family Cryptodifflugiidae Jung, 1942

Genus Cryptodifflugia Penard, 1890

Genus Meisterfeldia Bobrov, 2016

Genus Wailesella Deflandre,1928

Incertae sedis Arcellinida, Genera: Argynnia Vucetich, 1974; Awerintzewia Schouteden, 1906; Geamphorella Bonnet, 1959; Jungia Loeblich and Tappan, 1961; Lagenodifflugia Medioli and Scott, 1983; Lamtoquadrula Bonnet, 1974; Leptochlamys West, 1901; Maghrebia Gauthier-Lièvre et Thomas, 1958; Pentagonia Gauthier-Lièvre et Thomas, 1958 ; Physochila Jung, 1942; Pontigulasia Rhumbler, 1896; Pseudawerintzewia Bonnet, 1959; Schoenbornia Decloitre, 1964; Schwabia Jung, 1942; Sexangularia Awerintzew, 1906, Zivkovicia Ogden, 1987.

Incertae sedis Amoebozoa, Genera: Microcorycia Cockerell, 1911; Parmulina Penard, 1902; Penardochlamys Deflandre, 1953; Zonomyxa Nüsslin, 1882

Domain Diaphoretickes Adl et al., 2012

Supergroup Sar Burki et al., 2008, emend. Adl et al., 2012

Phylum Stramenopiles Patterson, 1989, emend. Adl et al., 2005

Class Labyrinthulomycetes Dick, 2001

Order Amphitremida Poch, 1913, emend. Gomaa et al., 2013

Family Amphitrematidae Poch, 1913

Genus Amphitrema Archer, 1869

Genus Archerella Loeblich and Tappan, 1961

Genus Paramphitrema Valkanov, 1970

Supergroup Rhizaria Cavalier-Smith, 2002

Phylum Cercozoa Cavalier-Smith, 1998, emend. Adl et al., 2005; emend. Cavalier-Smith, 2018

Class Thecofilosea Cavalier-Smith, 2003, emend. Cavalier-Smith, 2011

Order Cryomonadida Cavalier-Smith, 1993

Family Rhogostomidae Dumack et al., 2017

Genus Capsellina Penard, 1909

Genus Rhogostoma Belar, 1921

Genus Sacciforma Dumack et al., 2017

Order Tectofilosida Cavalier-Smith, 2003

Family Chlamydophryidae de Saedeleer, 1934

Genus Chlamydophrys Cienkowsky, 1876

Genus Clypeolina Penard, 1902

Genus Diaphorodon Archer, 1869

Genus Lecythium Hertwig and Lesser, 1874

Genus Leptochlamydophris Belar, 1921

Family Pseudodifflugiidae de Saedeleer, 1934

Genus Pseudodifflugia Schlumberger, 1845

Class Silicofilosea Adl et al., 2005, emend. Adl et al., 2012

Order Thaumatomonadida Shirkina, 1987

Family Thaumatomonadidae Hollande, 1952

Genus Penardeugenia Deflandre, 1958

Order Euglyphida Copeland, 1956, emend. Cavalier-Smith, 1997

Family Assulinidae Lara et al., 2007

Genus Assulina Ehrenberg, 1872

Genus Placocista Leidy, 1879

Genus Valkanovia Tappan, 1966

Family Euglyphidae Wallich, 1864, emend. Lara et al., 2007

Genus Euglypha Dujardin, 1841

Genus Scutiglypha Foissner and Schiller, 2001

Family Sphenoderiidae Chatelain et al., 2013

Genus Deharvengia Bonnet, 1979

Genus Sphenoderia Schlumberger, 1845

Genus Trachelocorythion Bonnet, 1979

Family Trinematidae Hoogenraad and De Groot,1940, emend Adl et al., 2012

Genus Corythion Taranek, 1881

Genus Pileolus Coûteaux et Chardez, 1981

Genus Playfairina Thomas, 1961

Genus Puytoracia Bonnet, 1970

Genus Trinema Dujardin, 1841

Family Cyphoderiidae de Saedeleer, 1934

Genus Campascus Leidy, 1877

Genus Chardezia Golemansky, 1970

Genus Corythionella Golemansky, 1970

Genus Cyphoderia Schlumberger, 1845

Genus Messemvriella Golemansky, 1973

Genus Pseudocorythion Valkanov, 1970

Genus Schaudinnula Awerintzev, 1907

Family Paulinellidae de Saedeller 1934, emend. Adl et al. 2012

Genus Micropyxidiella Tarnawski and Lara, 2015

Genus Ovulinata Anderson, Rogerson & Hannah, 1997

Genus Paulinella Lauterborn, 1895

Incertae sedis Euglyphida, Genera: Ampullataria van Oye, 1956; Euglyphidion Bonnet, 1960; Heteroglypha Thomas et Gauthier-Lièvre, 1959; Matsakision Bonnet, 1967; Pareuglypha Penard, 1902; Tracheleuglypa Deflandre, 1928

Incertae sedis Cercozoa:

Family Psammonobiotidae Golemansky, 1974, emend. Meisterfeld, 2002

Genus Alepiella Golemansky, 1970

Genus Centropyxiella Valkanov, 1970

Genus Edaphonobiotus Schönborn, Foissner and Meisterfeld, 1983

Genus Micramphora Valkanov, 1970

Genus Micropsammella Golemansky, 1970

Genus Nadinella Penard, 1902

Genus Ogdeniella Golemansky, 1982

Genus Psammonobiotus Golemansky, 1967

Genus Propsammonobiotus Golemansky, 1991

Family Volutellidae Sudzuki, 1979

Genus Pseudovolutella Sudzuki, 1979

Genus Volutella Chardez, 1977

Incertae sedis Cercozoa, Genera: Feuerbornia Jung, 1942; Frenzelina Penard, 1902; Lesquerella Chardez et Thomas, 1980; Rhumbleriella Golemansky, 1970

List of Sphagnum-dwelling testate amoebae recorded in Bulgaria

Prior to our investigation, the number of known Sphagnum-dwelling testate amoebae in Bulgaria was 171 (Bankov et al. 2018). Present study increases the number with 4 species and this group currently comprises 175 species classified into 45 genera, 20 families, six orders, five classes and three phyla. The species are presented in a systematic order, according to the classification in the previous chapter.

Varieties and forms recorded from Bulgaria are not included separately in the atlas, despite the fact that, according to the International Code of Zoological Nomenclature, article 45.6.3, when the name was published before 1961 using the abbreviation ‘var.’ or ‘f.’, it is deemed to be subspecific rather than infrasubspecific. However, due to the fact that many of these taxa have not sufficiently detailed descriptions and in many cases they are described on a basis of traits that do not have much taxonomic significance (small differences in size, the presence or absence of spines/cornes and their number, the number of lobes of the aperture, etc.) these taxa remain with unclear taxonomic status. So, until the clarifying of their status with the help of combined morphological and molecular approaches and full confirmation of their validity, we prefere to adopt a conservative position and consider these taxa as the product of the phenotipic plasticity of a nominal species. Nevertheless, in the next chapter “Species descriptions and illustrations” to each nominal species, in ‘Notes’, we have included all the records for these infrasubspecific taxa, in the event that some of them may be raised in rank in the future.

Amoebozoa

Family Arcellidae

Genus Arcella

  • Arcella arenaria Greeff, 1866
  • Arcella bathystoma Deflandre, 1928
  • Arcella catinus Penard, 1890
  • Arcella dentata Ehrenberg, 1838
  • Arcella discoides Ehrenberg, 1871
  • Arcella gibbosa Penard, 1890
  • Arcella hemisphaerica Perty, 1852
  • Arcella intermedia (Deflandre, 1928) Tsyganov and Mazei, 2006
  • Arcella rotundata Playfair, 1918
  • Arcella vulgaris Ehrenberg, 1830

Family Netzeliidae

Genus Cyclopyxis

  • Cyclopyxis arcelloides (Penard, 1902) Deflandre, 1929
  • Cyclopyxis eurystoma Deflandre, 1929
  • Cyclopyxis kahli Deflandre, 1929
  • Cyclopyxis pirini Golemansky, 1974
  • Cyclopyxis puteus Thomas, 1960

Genus Netzelia

  • Netzelia oviformis (Cash, 1909) Ogden, 1979
  • Netzelia tuberculata (Wallich, 1864) Netzel, 1983

Incertae sedis Sphaerothecina

Genus Trigonopyxis

  • Trigonopyxis arcula (Leidy, 1879) Penard, 1912

Family Difflugiidae

Genus Difflugia

  • Difflugia acuminata Ehrenberg, 1838
  • Difflugia ampullula Playfair, 1918
  • Difflugia angulostoma Gauthier-Lièvre and Thomas, 1958
  • Difflugia bacillariarum Perty, 1849
  • Difflugia brevicolla Cash, 1909
  • Difflugia bryophila (Penard, 1902) Jung, 1942
  • Difflugia distenda Ogden, 1983
  • Difflugia elegans Penard, 1890
  • Difflugia glans Penard, 1902
  • Difflugia globulosa Dujardin, 1837
  • Difflugia hiraethogii Ogden, 1983
  • Difflugia lanceolata Penard,1890
  • Difflugia lobostoma Leidy, 1874
  • Difflugia lucida Penard, 1890
  • Difflugia mammillaris Penard, 1893
  • Difflugia mica Frenzel, 1892
  • Difflugia microclaviformis (Kourov, 1925) Ogden, 1983
  • Difflugia minuta Rampi, 1950
  • Difflugia molesta Penard, 1902
  • Difflugia oblonga Ehrenberg, 1838
  • Difflugia penardi Hopkinson,1909
  • Difflugia petricola Cash, 1909
  • Difflugia pristis Penard, 1902
  • Difflugia pulex Penard, 1902
  • Difflugia pyriformis Perty, 1849
  • Difflugia rotunda (Chardez, 1956) Ogden, 1983
  • Difflugia rubescens Penard, 1891
  • Difflugia stoutii Ogden, 1983
  • Difflugia subaequalis Penard, 1910
  • Difflugia urceolata Carter, 1864
  • Difflugia ventricosa Deflandre, 1926
  • Difflugia viscidula Penard, 1902

Family Lesquereusiidae

Genus Lesquereusia

  • Lesquereusia epistomium Penard, 1902
  • Lesquereusia gibbosa Thomas et Gauthier-Lièvre, 1859
  • Lesquereusia modesta Rhumbler, 1896
  • Lesquereusia spiralis (Ehrenberg, 1840) Bütschli, 1880

Family Centropyxidae

Genus Centropyxis

  • Centropyxis aculeata (Ehrenberg, 1830) Stein, 1857
  • Centropyxis aerophila Deflandre, 1929
  • Centropyxis cassis (Wallich, 1864) Deflandre, 1929
  • Centropyxis constricta (Ehrenberg, 1838) Penard, 1902
  • Centropyxis cryptostoma Bonnet, 1959
  • Centropyxis discoides (Penard, 1890) Deflandre, 1929
  • Centropyxis ecornis (Ehrenberg, 1841) Leidy, 1879
  • Centropyxis elongata (Penard, 1890) Thomas, 1959
  • Centropyxis gibba Deflandre, 1929
  • Centropyxis hirsuta Deflandre, 1929
  • Centropyxis laevigata Penard, 1890
  • Centropyxis minuta Deflandre, 1929
  • Centropyxis orbicularis Deflandre, 1929
  • Centropyxis plagiostoma Bonnet et Thomas, 1955
  • Centropyxis platystoma (Penard, 1890) Deflandre, 1929
  • Centropyxis spinosa (Cash, 1905) Deflandre, 1929
  • Centropyxis sylvatica (Deflandre, 1929) Bonnet et Thomas, 1955

Family Plagiopyxidae

Genus Bullinularia

  • Bullinularia indica (Penard, 1907) Deflandre, 1953

Genus Plagiopyxis

  • Plagiopyxis callida Penard, 1910
  • Plagiopyxis declivis Thomas, 1955
  • Plagiopyxis glyphostoma Bonnet, 1959
  • Plagiopyxis labiata Penard, 1910
  • Plagiopyxis minuta Bonnet, 1959
  • Plagiopyxis oblonga (Bonnet et Thomas, 1955)

Family Hyalospheniidae

Genus Alabasta

  • Alabasta militaris (Penard, 1890) Duckert, Blandenier, Kosakyan and Singer, 2018

Genus Gibbocarina

  • Gibbocarina galeata (Penard, 1890) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016

Genus Hyalosphenia

  • Hyalosphenia elegans (Leidy, 1874) Leidy, 1879
  • Hyalosphenia papilio (Leidy, 1874) Leidy, 1875

Genus Longinebela

  • Longinebela ampulla Todorov, Bankov and Ganeva, 2018
  • Longinebela golemanskyi (Todorov, 2010) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016
  • Longinebela penardiana (Deflandre, 1936) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016
  • Longinebela speciosa (Deflandre, 1936) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016
  • Longinebela tubulosa (Penard, 1902) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016

Genus Nebela

  • Nebela aliciae Mitchell et Lara, 2013
  • Nebela collaris (Ehrenberg 1848) Leidy, 1879
  • Nebela flabellulum Leidy, 1874
  • Nebela guttata Kosakyan and Lara, 2013
  • Nebela pechorensis Kosakyan et Mitchell, 2013
  • Nebela rotunda Penard, 1890
  • Nebela tincta (Leidy, 1879) Awerintzew, 1906

Genus Padaungiella

  • Padaungiella americana (Taranek, 1882)
  • Padaungiella lageniformis (Penard, 1890) Lara et Todorov, 2012
  • Padaungiella nebeloides (Gauthier-Lièvre et Thomas, 1958) Lara et Todorov, 2012
  • Padaungiella tubulata (Brown, 1911) Lara et Todorov, 2012
  • Padaungiella wailesi (Deflandre, 1936) Lara et Todorov, 2012

Genus Planocarina

  • Planocarina carinata (Archer, 1867) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016

Genus Quadrulella

  • Quadrulella longicollis (Taranek, 1882)
  • Quadrulella symmetrica (Wallich, 1864) Cockerell, 1909
  • Quadrulella tubulata Gauthier-Lièvre, 1953
  • Quadrulella variabilis Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016

Family Heleoperidae

Genus Heleopera

  • Heleopera petricola Leidy, 1879
  • Heleopera rosea Penard, 1890
  • Heleopera sphagni (Leidy, 1874)
  • Heleopera sylvatica Penard, 1890

Family Microchlamyidae

Genus Microchlamys

  • Microchlamys patella (Claparede and Lachmann, 1859) Cockerell, 1911

Genus Pyxidicula

  • Pyxidicula patens (Claparede and Lachmann, 1858)

Family Phryganellidae

Genus Phryganella

  • Phryganella acropodia (Hertwig and Lesser, 1874) Hopkinson, 1909
  • Phryganella hemisphaerica (Penard, 1890) Penard, 1902
  • Phryganella nidulus Penard, 1902
  • Phryganella paradoxa Penard, 1902

Family Cryptodifflugiidae

Genus Cryptodifflugia

  • Cryptodifflugia compressa Penard, 1902
  • Cryptodifflugia oviformis Penard, 1890

Genus Wailesella

  • Wailesella eboracensis (Wailes and Penard, 1911) Deflandre, 1928

Incertae sedis Arcellinida

Genus Argynnia

  • Argynnia bipes (Carter, 1870) Murray, 1870
  • Argynnia dentistoma (Penard, 1890)
  • Argynnia vitraea (Penard, 1899)

Genus Awerintzewia

  • Awerintzewia cyclostoma (Penard, 1902) Schouteden, 1906

Genus Lagenodifflugia

  • Lagenodifflugia bryophila (Penard, 1902) Ogden, 1987
  • Lagenodifflugia montana (Ogden and Zivkovic, 1983) Ogden, 1987
  • Lagenodifflugia vas (Leidy, 1874) Medioli and Scott, 1983

Genus Pontigulasia

  • Pontigulasia elisa (Penard, 1893) Schouteden, 1906
  • Pontigulasia rhumbleri Hopkinson, 1919

Genus Zivkovicia

  • Zivkovicia compressa (Carter, 1864)
  • Zivkovicia spectabilis (Penard, 1902) Ogden, 1987

Incertae sedis Amoebozoa

Genus Microcorycia

  • Microcorycia flava (Greeff, 1866), emend. Penard, 1902

Stramenopiles

Family Amphitrematidae

Genus Archerella

  • Archerella flavum (Archer, 1877) Loeblich and Tappan, 1961

Cercozoa

Family Chlamydophryidae

Genus Lecythium

  • Lecythium mutabilis (Bailey, 1853)

Family Pseudodifflugiidae

Genus Pseudodifflugia

  • Pseudodifflugia fascicularis Penard, 1902
  • Pseudodifflugia gracilis Schlumberger, 1845

Family Assulinidae

Genus Assulina

  • Assulina muscorum Greeff, 1888
  • Assulina seminulum (Ehrenberg, 1848) Leidy, 1879

Genus Placocista

  • Placocista glabra Penard, 1906
  • Placocista spinosa (Carter, 1865) Leidy, 1879

Family Euglyphidae

Genus Euglypha

  • Euglypha acanthophora (Ehrenberg, 1841) Perty, 1849
  • Euglypha aspera Penard, 1899
  • Euglypha bryophila Brown, 1911
  • Euglypha ciliata (Ehrenberg, 1848), Leidy, 1878
  • Euglypha compressa Carter, 1864
  • Euglypha cristata Leidy, 1874
  • Euglypha denticulata Brown, 1912
  • Euglypha filifera Penard, 1890
  • Euglypha laevis (Ehrenberg, 1845) Perty, 1849
  • Euglypha rotunda Wailes and Penard, 1911
  • Euglypha strigosa (Ehrenberg, 1871) Leidy, 1878
  • Euglypha tuberculata Dujardin, 1841

Genus Scutiglypha

  • Scutiglypha crenulata (Wailes, 1912) Foissner and Schiller, 2001

Family Sphenoderiidae

Genus Sphenoderia

  • Sphenoderia fissirostris Penard, 1890
  • Sphenoderia labiata Thomas et Gauthier-Lièvre, 1959
  • Sphenoderia lenta Schlumberger, 1845
  • Sphenoderia minuta Deflandre, 1931
  • Sphenoderia ovoidea Jung, 1942
  • Sphenoderia splendida (Playfair, 1917) Deflandre, 1931

Genus Trachelocorythion

  • Trachelocorythion pulchellum (Penard, 1890) Bonnet, 1979

Family Trinematidae

Genus Corythion

  • Corythion constricta (Certes, 1889) Jung, 1942
  • Corythion delamarei Bonnet et Thomas, 1960
  • Corythion dubium Taránek, 1881

Genus Playfairina

  • Playfairina valkanovi Golemansky, 1966

Genus Trinema

  • Trinema complanatum Penard, 1890
  • Trinema enchelys (Ehrenberg, 1838) Leidy, 1878
  • Trinema galeata (Penard, 1890) Jung, 1942
  • Trinema grandis (Chardez, 1960) Golemansky, 1963
  • Trinema lineare Penard, 1890

Family Cyphoderiidae

Genus Campascus

  • Campascus minutus Penard, 1899
  • Campascus triqueter Penard, 1891

Genus Cyphoderia

  • Cyphoderia amphoralis (Wailes and Penard, 1911)
  • Cyphoderia ampulla (Ehrenberg, 1840) Leidy, 1878
  • Cyphoderia major (Penard, 1891)

Family Paulinellidae

Genus Paulinella

  • Paulinella chromatophora Lauterborn, 1895

Incertae sedis Euglyphida

Genus Pareuglypha

  • Pareuglypha reticulata Penard, 1902

Genus Tracheleuglypha

  • Tracheleuglypha acolla Bonnet et Thomas, 1955
  • Tracheleuglypha dentata (Moniez, 1888) Deflandre, 1928

Species descriptions and illustrations

A total of 120 species are described in the atlas, including most of the characteristic sphagnicolous testate amoebae, as well as some rare or accidentally found in Sphagnum mosses species. The following information is given for each species: description; ecology; geographical distribution; distribution in Sphagnum mosses in Bulgaria and relevant literature sources; morphometric characterisation; taxonomic notes (if necessary); synonymous names (if available); original publication and publication where last revision is made (if any).

Each species is illustrated by nine micrographs, primarily on scanning electron microscope (SEM), to receive information about the shell ultrastructure. Micrographs taken on light microscope (LM) are additionally given for most of them to illustrate the cytoplasm and pseudopodia of live individuals.

In measurements of the species in which the aboral protuberances or horns (spines) are present, the length includes these appendages when they are part of the shell matrix (e.g. Centropyxis, Difflugia, Pareuglypha), but excludes them when they are specialised shell components (e.g. Euglypha).

Arcella arenaria Greeff, 1866

Original description: Greeff 1866, Archiv für Mikroskopische Anatomie, 2, p. 330, Taf. XVIII, Fig. 16.

Synonyms: Arcella aureola Maggi, 1883; Arcella microstoma Penard, 1890.

Description: Shell yellow or light brown, circular, with depressed aboral region and conical in lateral view (Fig. 11 A-G). Apertural surface smooth, with small pores around the basal border (Fig. 11 D, H). Shell composed of very small organic alveoli of about 0.5-0.6 μm in diameter (Fig. 11 I). Aperture invaginated, circular, bordered by a distinct lip and corone of about ten to fifteen large pores (Fig. 11 D, H). Cytoplasm abundant, does not fills the whole shell; often amoebae are encysted with large spheroidal cyst and characteristic rejected apertural side (Fig. 11 G). Two typical vesicular nuclei of about 20 μm, with a single central nucleolus. Pseudopodia few, large, rarely exceed the basal border; movement slow, with sliding on the substrate.

Notes: A. arenaria is similar to A. catinus, but these two species may be distinguished by the size (A. catinus is bigger, with larger aperture), number of apertural pores (10-15 in A. arenaria, versus 18-35 in A. catinus), as well as by theirs ecology: A. arenaria inhabits mostly aerophilic and dry habitats, whereas A. catinus occurs in wet habitats, mainly wet Sphagnum mosses.

Ecology: Common in aerophilic mosses and litter in deciduous forests, very rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990).

Arcella arenaria. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 93.4 89.8 12.65 2.31 14.01 70 119 30
Diameter of aperture 17.4 17.1 3.88 0.71 22.32 13 28 30
Depth 29.6 27.6 4.66 1.41 15.77 26 40 11
Aperture/Diameter ratio 0.19 0.19 0.03 0.006 15.97 0.1 0.3 30
Depth/Diameter ratio 0.32 0.29 0.09 0.03 28.30 0.3 0.6 11
Figure 11.

Light (A, B) and scanning electron (C-I) micrographs of Arcella arenaria. (A-C) View of many specimens showing variability in shape and size of the shell. (D) Apertural view to show smooth apertural surface. (E-F) Aboral view showing depressed segments of surface. (G) Lateral view. (H) Close up view of aperture to show distinct apertural lip and surrounding large pores. (I) Portion of shell surface showing small organic alveoli on the aboral surface.

Arcella bathystoma Deflandre, 1928

Original description: Deflandre 1928, Archiv für Protistenkunde, 64, p. 237, Fig. 242–243.

Description: Shell yellow or light brown, circular in apertural and dorsal view; with a shallow domed or conical aboral region in lateral view, and sides running evenly down at slightly rounded angles to the apertural side (Fig. 12 A-F). Apertural surface and basal border smooth (Fig. 12 C, D); aboral surface with series of fine depressions of about 5-8 μm, inconspicuous at small magnification (Fig. 12 E, H-I). Shell composed of regularly arranged small organic alveoli of about 0.6-0.8 μm (Fig. 12 H, I). Aperture deeply invaginated, up to half of the depth, circular and bordered by a very small lip and about ten to twenty large pores, sometimes not well visible (Fig. 12 G). Cytoplasm does not fills the whole shell; cell fixed with numerous fine epipodes at the shell wall; two typical vesicular nuclei with a single central nucleolus. Pseudopodia three to four, short, finger-like, rarely exceed the basal border; movement slow, with sliding on the substrate.

Ecology: In Sphagnum, rare, low population density.

Geographical distribution: Possible cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rila Mts. (Bankov et al. 2018).

Arcella bathystoma. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 62.7 60.3 7.54 1.14 12.02 52 78 44
Diameter of aperture 21.1 21.1 3.06 0.46 14.49 14 29 44
Depth 24.4 24.2 5.03 0.83 20.6 16 35 37
Aperture/Diameter ratio 0.34 0.34 0.03 0.005 10.27 0.2 0.4 44
Depth/Diameter ratio 0.39 0.38 0.06 0.010 16.16 0.24 0.53 37
Figure 12.

Light (A) and scanning electron (B-I) micrographs of Arcella bathystoma. (A-B) View of several specimens showing general shape of the shell. (C, D) Apertural view of two specimens to show deeply invaginated and comparatively large aperture. (E) Dorsal view showing regular depressions on aboral shell surface. (F) Lateral view. (G) Close up view of aperture to show apertural lip and surrounding large pores. (H, I) Portion of shell surface showing arrangement of the organic alveoli and regular depressions on the aboral surface of the shell.

Arcella catinus Penard, 1890

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 154, Pl. V, fig. 78 à 92.

Synonyms: Arcella vulgaris Leidy, 1879 (in part); Arcella artocrea Penard, 1902; Arcella vulgaris var. compressa Cash, 1905; Arcella catinus var. australis Playfair, 1918

Description: Shell yellow or light brown, too variable in shape - circular, oval, triangular, quadrangular, more or less irregular in apertural and dorsal view (Fig. 13 A-F); with depressed aboral region and trapezoidal in lateral view (Fig. 13 G). Apertural surface smooth, with small pores around the basal border (Fig. 13 F); dorsally divided into segments by folding of the surface, with view of polygon or a star (Fig. 13 C-E, H). Shell composed of very small organic alveoli of about 0.5-0.6 μm (Fig. 13 H). Aperture s invaginated, circular or oval, bordered by a distinct lip and corone of about fifty to twenty large pores (Fig. 13 F, I). Cytoplasm abundant but not fill the whole shell; often amoebae are encysted, with large spheroidal cyst and characteristic rejected apertural side; two typical vesicular nuclei of about 16-18 μm, with a single central nucleolus. Pseudopodia few, large, exceed the basal border; movement slow, with sliding on the substrate.

Notes: A. catinus is similar to A. arenaria, but these two species may be distinguished by the size (A. catinus is bigger, with larger aperture), number of apertural pores (10-15 in A. arenaria, versus 18-35 in A. catinus), as well as by theirs ecology: A. arenaria inhabits mostly aerophilic and dry habitats, whereas A. catinus occurs mainly in Sphagnum mosses.

Ecology: Frequent in wet Sphagnum mosses.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1928, Golemansky 1965, Golemansky and Todorov 1990, Todorov 1993, Todorov and Golemansky 1995; Bankov et al. 2018).

Arcella catinus. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 120.6 119.8 9.74 1.78 8.07 101 137 30
Breadth 100.3 100.2 8.16 1.49 8.14 86 120 30
Depth 52.7 53.8 7.04 1.35 13.4 36 68 27
Large axis of aperture 29.4 30.6 3.70 0.67 12.6 22 37 30
Small axis of aperture 23.0 22.7 3.22 0.59 14.0 16 30 30
Depth/Length ratio 0.44 0.44 0.06 0.011 13.18 0.3 0.6 27
Figure 13.

Light (A, B) and scanning electron (C-I) micrographs of Arcella catinus. (A-C) View of many specimens showing variability in shape and size of the shell. (C-E) Dorsal view to illustrate depressed aboral region and foldings of the surface; (F) Apertural view to show smooth apertural surface; (G) Lateral view showing characteristic trapezoidal shape. (H) Portion of shell surface showing small organic alveoli and foldings of the aboral surface. (I) Close up view of aperture to show distinct apertural lip and surrounding large pores.

Arcella dentata Ehrenberg, 1830

Original description: Ehrenberg 1830, Abhandlungen der Königlichen Akademie der Wissenszchaften zu Berlin, p. 40.

Synonyms: Arcella stellaris Perty, 1852; Arcella Okeni Perty, 1852; Arcella stellata Ehrenberg, 1854

Description: Shell colorless in young and yellow or brown in older individuals; circular and more or less dentate seen from above or below (Fig. 14 A-E). In lateral view resembles a crown with evenly rounded top and turned-up rim edged with conical points of variable length. Shallow conical aboral region, frequently depressed at summit, with a series of radiating ridges curving to the points of the rim (Fig. 14 F, I). Number of ridges varies, usually from nine to fourteen. Shell depth about one third of the shell diameter. Apertural surface invaginated, usually smooth, with numerous small pores. Aperture invaginated, circular, with small lip and surrounded by about forty to sixty large pores (Fig. 14 E, G). Shell composed of small round alveoli of about 1 μm in diameter (Fig. 14 H). Cell does not fill the shell, fixed at the shell wall with many small epipodes; usually one, rarely few, short granular endolobopodia and two typical vesicular nuclei with one large central nucleolus (Fig. 14 C).

Ecology: Weakly mineralized peat bogs and lakes, Sphagnum spp.; comparatively rare and usually with a low density.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mt. (Bankov et al. 2018); Rhodopes Mt. (Pateff 1924, Golemansky et al. 2006).

Arcella dentata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 140.0 141.0 10.20 1.19 7.29 96 161 73
Diameter of aperture 44.9 44.5 4.27 0.50 9.52 35 58 72
Depth 37.8 37.4 2.92 0.81 7.72 33 44 13
Aperture/Diameter ratio 0.32 0.32 0.03 0.004 9.32 0.3 0.4 72
Depth/Diameter ratio 0.27 0.26 0.02 0.004 6.08 0.2 0.3 13
Figure 14.

Light (A, C) and scanning electron (B, D-I) micrographs of Arcella dentata. (A, B) View of many specimens showing variability in shape and size of the shell. (C) View of live specimen illustrating two typical vesicular nuclei with one large central nucleolus, numerous small epipodes and granular endolobopodia. (D) Dodsal view showing shell depression on top and radiating ridges. (E) Apertural view. (F) Lateral view showing characteristic crown resembling shell. (G) View of aperture to illustrate small lip and surrounding large pores. (H) Portion of shell surface to show structuring alveoli and small pores. (I) Lateral view showing highly flattened shell with turned-up rim edged with conical point.

Arcella discoides Ehrenberg, 1871

Original description: Ehrenberg 1871, Abhandlungen der Königliche Akademie der Wissenshaften zu Berlin (1871), p. 259, Taf. III, fig. 1.

Synonyms: Arcella discoidea Ehrenberg, 1843.

Description: Shell yellow or brown, circular, with shallow conical aboral region and basal border, discoid in lateral view (Fig. 15 A-F). Composed of very small organic alveoli of about 0.5-0.7 μm in diameter (Fig. 15 G-I). Aperture large, slightly invaginated, circular, bordered by a thin lip and corone of about fifty to seventy large pores (Fig. 15 D, G, H). Cytoplasm abundant, not fills the whole shell, attached to the walls with numerous short epipodes; two typical vesicular nuclei of about 20 μm in diameter with a single large, central nucleolus. Pseudopodia numerous, short, rarely exceed the basal border; movement slow, with sliding on the substrate (Fig. 15 A-C).

Ecology: Common in freshwater standing bodies, among aquatic vegetation, less frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Arcella discoides. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 116.2 117.9 14.63 2.63 12.59 91 144 31
Diameter of aperture 44.2 43.6 8.64 1.25 15.48 34 60 30
Depth 36.8 37.5 4.59 1.32 12.45 28 44 12
Aperture/Diameter ratio 0.38 0.37 0.04 0.007 9.39 0.3 0.5 30
Depth/Diameter ratio 0.34 0.33 0.05 0.01 13.52 0.2 0.4 12
Figure 15.

Light (A-C) and scanning electron (D-I) micrographs of Arcella discoides. (A) View of many specimens showing variability in shape and size of the shell. (B, C) View of live specimens illustrating numerous short epipodes and two typical vesicular nuclei with one large central nucleolus. (D) Apertural view to show smooth apertural surface, large aperture and surrounding numerous pores. (E) Aboral view. (F) Lateral view. (G, H) Close up view of aperture to show its circular outline, thin apertural lip and numerous surrounding large pores. (I) Portion of shell surface showing small organic alveoli on the aboral surface.

Arcella gibbosa Penard, 1890

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 155, Pl. V, fig. 96 à 99, Pl. VI, fig. 1.

Description: Shell yellow or brown, circular, with depressed aboral region and domed or hemispherical in lateral view (Fig. 16 A-G). Apertural surface and the basal collar are smooth (Fig. 16 B, D, F). Shell composed of small organic alveoli of about 1-1,2 μm in diameter (Fig. 16 G-I). Aperture invaginated, circular, bordered by a distinct lip (Fig. 16 B, D, G). Cytoplasm abundant, does not fills the whole shell; cell attached to the walls with numerous short epipodes; two typical vesicular nuclei with a single central nucleolus. Pseudopodia numerous, short, rarely exceed the basal border; movement slow, with sliding on the substrate (Fig. 16 A, C).

Ecology: In freshwater standing bodies, among aquatic vegetation, rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky et al. 2006); Vitosha Mts. (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Arcella gibbosa. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 98,7 98,6 4,79 1,05 4,85 91 106 21
Diameter of aperture 20,9 20,6 1,64 0,36 7,85 19 25 21
Depth 52,5 52,3 1,80 0,39 3,43 49 57 21
Aperture/Diameter ratio 0,21 0,21 0,008 0,002 3,81 0,20 0,23 21
Depth/Diameter ratio 0,53 0,53 0,017 0,004 3,21 0,50 0,56 21
Figure 16.

Light (A, C) and scanning electron (B, D-I) micrographs of Arcella gibbosa. (A, B) View of many specimens showing variability in shape and size of the shell. (C) View of live specimen illustrating numerous short epipodes and two typical vesicular nuclei with one large central nucleolus. (D) Latero-apertural view to show smooth apertural surface and invagited aperture. (E) Dorsal view showing depressed segments of the surface. (F) Lateral view. (G) Close up view of aperture to show distinct apertural lip. (H) Close up view of aboral side showing depressed segments of the surface. (I) Portion of shell surface showing small organic alveoli and numerous surrounding small pores.

Arcella hemisphaerica Perty, 1852

Original description: Perty 1852, Zur Kenntnis kleinster Lebensformen, p. 186, T. 9, fig. 5.

Synonyms: Arcella vulgaris var. hemisphaerica Wailes, 1918

Description: Shell yellow or brown, smooth or irregular, circular in apertural or aboral view, hemispherical in lateral view; with sides running evenly down at nearly right or slightly rounded angles to the apertural side (Fig. 17 A-H); composed of comparatively large organic alveoli, easily collapsed when the shell is dryied, with numerous small pores (Fig. 17 I). Aperture slightly invaginated, circular and bordered by a small lip (Fig. 17 D, E, I). Cytoplasm does not fill the shell, cell fixed with numerous fine epipodes at the shell walls; two vesicular nuclei with a single large, central and spherical nucleolus (Fig. 17 C). Pseudopodia usually two to four, short, finger-like, rarely go beyond the edge of the shell; movement slow, with sliding on the substrate.

Notes: The species has been recorded in both as nominal species and as infrasubspecific taxon Arcella hemisphaerica f. undulata Deflandre, 1928 (Rhodopes Mts., Rila Mts.).

Ecology: Common in stagnant freshwater bodies, in littoral zone among aquatic vegetation, less frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov 2004, Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Arcella hemisphaerica. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 57.4 54.7 6.66 1.03 11.60 49 71 42
Diameter of aperture 17.9 18.2 2.91 0.45 16.26 12 26 42
Depth 31.3 30.1 6.10 1.76 19.51 25 43 12
Aperture/Diameter ratio 0.31 0.30 0.04 0.006 11.56 0.3 0.4 42
Depth/Diameter ratio 0.57 0.56 0.06 0.018 10.91 0.5 0.7 12
Figure 17.

Light (A-C) and scanning electron (D-I) micrographs of Arcella hemisphaerica. (A, B) View of many specimens showing variability in shape and size of the shell. (C) View of live specimen illustrating numerous short epipodes and two typical vesicular nuclei with one large central nucleolus. (D, E) Apertural view of two specimens. (F) Dorsal view. (G, H) Latero-apertural view. (I) Close up view of aperture showing the apertural lip, irregular shell surface caused by drying of the shell and collapsed alveoli, as well as numerous small pores.

Arcella intermedia (Deflandre, 1928) Tsyganov and Mazei, 2006

Original description: Deflandre 1928, Archiv für Protistenkunde, 64, p. 215-216, Fig. 238–240; Last revision: Tsiganov and Mazei 2006, Protistology, 4 (4), p. 367, Fig. 5e.

Synonyms: Arcella hemisphaerica var. intermedia f. undulata Deflandre, 1928

Description: Shell yellow or brown, circular in apertural and dorsal view, domed or hemispherical in lateral view; with sides running evenly down by broadly rounded angles to the apertural side (Fig. 18 A-F). Apertural surface and basal border smooth (Fig. 18 C, D); aboral surface with series of regular depressions of about 10-15 μm (Fig. 18 E, F). Shell composed of regularly arranged hexagonal alveoli (about 1-1.5 μm), with numerous small pores (Fig. 18 H, I). Aperture invaginated, circular and bordered by a distinct lip (Fig. 18 G). Cytoplasm does not fills the whole shell; cell is fixed with numerous fine epipodes at the shell walls; binucleate, typical vesicular nuclei with a single central nucleolus. Pseudopodia few, very short, finger-like, usually does not exceed the basal border; movement slow, with sliding on the substrate.

Ecology: Common in stagnant freshwater bodies, among submerged aquatic vegetation; less common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Arcella intermedia. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 60.9 60.5 3.71 0.60 6.09 53 69 38
Diameter of aperture 16.0 16.0 1.49 0.24 9.33 14 23 38
Depth 34.0 34.0 2.46 0.40 7.21 29 39 37
Aperture/Diameter ratio 0.26 0.26 0.02 0.004 8.41 0.2 0.4 38
Depth/Diameter ratio 0.56 0.55 0.05 0.008 8.45 0.5 0.7 37
Figure 18.

Light (A, B) and scanning electron (C-I) micrographs of Arcella intermedia. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C) Latero-apertural view showing apertural invagination. (D) Apertural view to show smooth apertural surface. (E) Dorsal view showing regular depressions on aboral surface of the shell. (F) Lateral view. (G) Close up view of aperture to show the apertural lip. (H, I) Portion of shell surface showing regularity in arrangement of the organic hexagonal alveoli and numerous small pores.

Arcella rotundata Playfair, 1918

Original description: Playfair 1918, Proceedings of the Linnean Society of New South Wales, 42, p. 637, Pl. XXXIV, fig. 1.

Description: Shell yellow or brown, smooth, thin and fragile, circular in ventral view, domed or hemispherical in lateral view; margin of the dome without basal angles and merging into the base in a broadly rounded curve (Fig. 19 A-G); composed of many organic alveoli, arranged in a single layer and surrounded by numerous small pores (Fig. 19 I). Aperture invaginated, circular and bordered by a distinct lip (Fig. 19 C-E, H). Cytoplasm does not fill the shell; cell fixed with numerous short epipodes at the shell walls; two vesicular nuclei with a single large, central and spherical nucleolus. Pseudopodia usually three or four, short, finger-like; movement slow, with sliding on the substrate.

Notes: Besides the nominal species two infrasubspecific taxa have also been recorded in Bulgaria: Arcella rotundata var. stenostoma Deflandre, 1928 (Vitosha Mts.) and Arcella rotundata var. stenostoma f. undulata Deflandre, 1928 (Rhodopes Mts., Vitosha Mts.).

Ecology: Common in standing freshwater bodies, among submerged aquatic vegetation; less frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Arcella rotundata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 49.4 48.5 3.58 0.65 7.24 44 57 30
Diameter of aperture 14.5 13.9 2.58 0.47 17.8 10 21 30
Depth 30.0 23.1 3.26 0.59 13.6 19 31 30
Aperture/Diameter ratio 0.29 0.29 0.05 0.01 17.72 0.2 0.4 30
Depth/Diameter ratio 0.49 0.49 0.06 0.01 11.8 0.38 0.64 30
Figure 19.

Light (A) and scanning electron (B-I) micrographs of Arcella rotundata. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C-D) Apertural view of two specimens. (E) Latero-apertural view. (F) Dorsal view. (G) Lateral view. (H) Close up view of aperture showing the bordering lip. (I) Portion of shell surface to show arrangement of organic alveoli and numerous small pores.

Arcella vulgaris Ehrenberg, 1830

Original description: Ehrenberg 1830, Abhandlungen der Königlichen Akademie der Wissenszchaften zu Berlin, p. 40, 53, 61, 69, 70, 75, Taf. I, Fig. VI (1-3).

Description: Shell yellow or brown, circular and domed or hemispherical in lateral view, with pronounced basal collar (Fig. 20 A-G). Apertural surface and the basal collar smooth (Fig. 20 B, D, F). Shell composed of small organic alveoli of about 1-1,2 μm in diameter (Fig. 20 I). Aperture invaginated, circular, bordered by a distinct lip (Fig. 20 B, D, G, H). Cytoplasm abundant, does not fills the whole shell; cell fixed with numerous short epipodes at the shell walls; two typical vesicular nuclei with a single central nucleolus. Pseudopodia numerous, short, rarely exceed the basal border; movement slow, with sliding on the substrate (Fig. 20 C).

Ecology: Common in freshwater standing bodies, among aquatic vegetation, less frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky, 2000); Vitosha Mts. (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Arcella vulgaris. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 116.1 118.2 11.70 1.74 10.07 87 139 45
Diameter of aperture 35.9 38.2 6.50 1.02 18.10 23 49 41
Depth 62.7 62.4 4.48 1.16 7.14 57 74 15
Aperture/Diameter ratio 0.30 0.31 0.04 0.006 12.96 0.2 0.4 41
Depth/Diameter ratio 0.59 0.58 0.05 0.01 8.13 0.5 0.7 15
Figure 20.

Light (A, C) and scanning electron (B, D-I) micrographs of Arcella vulgaris. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C) View of live specimen illustrating numerous short epipodes and two typical vesicular nuclei with one large central nucleolus. (D) Apertural view to show smooth apertural surface and deeply invaginated aperture with pronounced apertural lip. (E) Dorsal view. (F, G) Lateral view showing a basal collar. (H) Close up view of aperture to show distinct apertural lip. (I) Portion of shell surface showing small organic alveoli and numerous surrounding small pores.

Cyclopyxis eurystoma Deflandre, 1929

Original description: Deflandre 1929, Archiv für Protistenkunde, 67, p. 371, fig. 168 à 171.

Synonyms: Centropyxis (Cyclopyxis) eurystoma Deflandre, 1929.

Description: Shell yellow or brown, circular in apertural and aboral views, hemispherical in lateral view (Fig. 21 A-F); composed mainly of small to medium pieces of quartz, so arranged to give a well defined and regular outline with a rough surface (Fig. 21 C-F). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 21 E, F, I). Aperture circular, central, well defined and bordered by smooth band of organic cement (Fig. 21 G, H).

Ecology: Frequent in soils, mosses and forest litter, rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Cyclopyxis eurystoma. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 59.3 57.5 7.14 1.28 12.03 50 78 31
Depth 42.9 42.9 5.98 1.11 13.93 33 56 29
Diameter of aperture 28.7 28.7 5.05 0.91 17.59 21 40 31
Depth/Diameter ratio 0.73 0.73 0.1 0.02 14.05 0.5 0.9 29
Aperture/Diameter ratio 0.48 0.48 0.05 0.009 9.99 0.4 0.6 31
Figure 21.

Light (A, B) and scanning electron (C-I) micrographs of Cyclopyxis eurystoma. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Apertural view showing general shape. (E) Dorsal view. (F) Lateral view. (G) Close up view of aperture. (H) Close up view of smooth apertural surface. (I) Detail of aboral side of the shell to illustrate its rough surface, covered with large pieces of quartz.

Cyclopyxis kahli Deflandre, 1929

Original description: Deflandre 1929, Archiv für Protistenkunde, 67, p. 370, fig. 164 à 167.

Synonyms: Centropyxis (Cyclopyxis) eurystoma Deflandre, 1929.

Description: Shell yellow or brown, circular in apertural and aboral views, hemispherical in lateral view (Fig. 22 A-G); composed mainly of small to medium pieces of quartz, so arranged to give a well defined and regular outline with a rough aboral surface and smooth apertural surface (Fig. 22 C-F). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 22 D-I). Aperture circular, central, well defined and bordered by quartz particles (Fig. 22 D, E, H).

Ecology: Frequent in soils, mosses and forest litter, rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Bankov et al. 2018).

Cyclopyxis kahli. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 87.9 88.7 8.31 1.49 9.56 71 106 31
Depth 60.7 59.5 7.96 1.45 13.11 46 88 30
Diameter of aperture 28.8 29.4 4.41 0.79 15.34 20 39 31
Depth/Diameter ratio 0.33 0.33 0.04 0.007 12.35 0.3 0.5 31
Aperture/Diameter ratio 0.69 0.70 0.07 0.01 10.46 0.6 0.9 30
Figure 22.

Light (A, C) and scanning electron (B, D-I) micrographs of Cyclopyxis kahli. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C-E) Apertural view of three specimens showing general shape. (F) Dorsal view. (G) Lateral view. (H) Close up view of aperture to illustrate its denticulate rim and smooth apertural surface. (I) Detail of aboral side of the shell to illustrate its rough surface, covered with large pieces of quartz.

Cyclopyxis puteus Thomas, 1960

Original description: Thomas 1960, Bulletin de la Société de Pharmacie de Bordeaux, 99, p. 14, fig. 1-4.

Description: Shell yellow or brown, circular in apertural and aboral views, hemispherical in lateral view (Fig. 23 A-G); composed mainly of small to medium pieces of quartz, embedded in deep layer of organic cement and so arranged to give a well defined and regular outline with a smooth surface (Fig. 23 C-G). Organic cement with numerous small pores on the apertural and lateral surface (Fig. 23 E, I). Aperture circular, central, well defined and deeply invaginated, forming an apertural tube and internal apertural opening (Fig. 23 D-F, H).

Ecology: In soils, mosses and forest litter, rarely and accidentally in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rila Mts. (Bankov et al. 2018).

Cyclopyxis puteus. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 155.7 155.4 9.26 1.16 5.95 133 179 64
Diameter of aperture 44.5 44.6 4.14 0.59 9.31 32 54 53
Internal opening 32.5 32.7 3.32 0.86 10.22 27 38 15
Depth 105.1 107.5 9.54 2.88 9.08 94 120 11
Aperture/Diameter ratio 0.28 0.29 0.02 0.003 7.02 0.2 0.3 37
Depth/Diameter ratio 0.70 0.70 0.03 0.01 4.56 0.6 0.8 11
Figure 23.

Light (A, B) and scanning electron (C-I) micrographs of Cyclopyxis puteus. (A, B) Light micrographs showing general shape. (C) View of many specimens to illustrate variability in shape and size of the shell (D-F) Apertural view of three specimens showing smooth apertural surface and deeply invaginated aperture. (G) Lateral view. (H) Close up view of aperture to illustrate its apertural tube and internal opening. (I) Detail of apertural side to illustrate its smooth surface and numerous pores in the organic cement.

Netzelia oviformis (Cash, 1909) Ogden, 1979

Original description: Cash and Hopkinson 1909, The British Freshwater Rhizopoda and Heliozoa. Vol. II, p. 52, Pl. XX, figs. 8-12; Last revision:Ogden 1979, Bulletin of the British Museum (Natural History), Zoology series, 36, p. 206.

Synonyms: Difflugia proteiformis subsp. globularis var. tuberculata Wallich, 1864; Difflugia tuberculata Archer, 1867; Difflugia lobostoma Leidy, 1879 (in part); Nebela tuberculata Owen and Jones, 1976; Difflugia tricuspis Medioli and Scott, 1983 (in part).

Description: Shell yellowish or brownish, circular in apertural and aboral views, ovoid or sub-spherical in lateral view (Fig. 24 A-F); composed of small siliceous particles, mixed with diatom frustules and boud by cement to produce a smooth surface (Fig. 24 D-I). Shell components usually in close contact with each other, small pores in the organic cement often seen (Fig. 24 H, I). Aperture terminal, with three or four lobes, bordered by a thick collar of organic cement or small siliceous particles (Fig. 24 D-H). Cytoplasm does not fills the whole shell; cell fixed with numerous long epipodes at the shell walls (Fig. 24 C). Pseudopodia usually two to four, long, fast moving (Fig. 24 A).

Ecology: Frequent in freshwater standing bodies, among aquatic vegetation, accidentally in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov 2004).

Netzelia oviformis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 103.3 102.0 11.88 1.73 11.50 85 129 47
Breadth 78.5 80.0 8.16 1.19 10.39 66 93 47
Diameter of aperture 25.9 25.0 2.68 0.39 10.34 22 33 47
Breadth /Length ratio 0.76 0.76 0.03 0.005 4.43 0.6 0.9 47
Aperture/Diameter ratio 0.33 0.34 0.03 0.004 8.12 0.3 0.4 47
Figure 24.

Light (A, C) and scanning electron (B, D-I) micrographs of Netzelia oviformis. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen to show numerous epipodes. (D, E) Lateral views of two specimens to show general shape. (F) Apertural view. (G) Close up view of aperture to illustrate four lobes of aperture and narrow collar of small siliceous particles. (H) Close up view of a narrow collar of small pieces of quartz. (H) Detail of shell surface to illustrate regular arrangement of siliceous particles.

Netzelia tuberculata (Wallich, 1864) Netzel, 1983

Original description: Wallich 1864, Annals and Magazine of Natural History, 13, p. 241, Pl. XV, fig. 4g, Pl. XVI, fig. 18; Last revision: Netzel 1983, Archiv für Protistenkunde, 127, p. 377.

Synonyms: Difflugia proteiformis subsp. globularis var. tuberculata Wallich, 1864; Difflugia tuberculata Archer, 1867; Difflugia lobostoma Leidy, 1879 (in part); Nebela tuberculata Owen and Jones, 1976; Difflugia tricuspis Medioli and Scott, 1983 (in part).

Description: Shell brownish, opaque, circular in apertural and aboral views, ovoid or spherical in lateral view (Fig. 25 A-E); composed of small quartz particles, aggregated in regularly arranged protrubences (Fig. 25 B, D-H). Shell components usually in close contact with each other, single meshs of organic cement rarely visible between particles (Fig. 25 I). Aperture terminal, lobed and bordered by a collar of small pieces of quartz (Fig. 25 D-G). Cytoplasm does not fills the whole shell; cell fixed with numerous long epipodes at the shell walls. Pseudopodia usually two to four, long, fast moving (Fig. 25 A, C).

Ecology: Frequent in freshwater standing bodies, accidentally in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov 2004).

Netzelia tuberculata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 123.9 119.5 12.48 1.60 10.07 111 153 61
Breadth 112.4 106.5 12.06 1.54 10.73 99 146 61
Diameter of aperture 34.4 33.5 3.86 0.49 11.24 29 42 61
Breadth /Length ratio 0.91 0.91 0.03 0.004 3.44 0.83 0.97 61
Aperture/Diameter ratio 0.31 0.30 0.03 0.004 11.04 0.2 0.4 61
Figure 25.

Light (A, C) and scanning electron (B, D-I) micrographs of Netzelia tuberculata. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen to show protruding pseudopods from the aperture. (D) Lateral view. (E) Apertural view showing general shape, as well as multilobed aperture. (F) Close up view of aperture to illustrate a narrow collar of small pieces of quartz and lobed aperture. (G) Close up view of a narrow collar of small pieces of quartz. (H) Detail of aboral side of the shell to illustrate regular arrangement of small protrubences. (I) Close up view of organic cement.

Trigonopyxis arcula (Leidy, 1879) Penard, 1912

Original description: Leidy 1879, Report of the United States Geological Survey of the Territories, 12, p. 116, Pl. XV, figs. 34-37, Pl. XVI, figs. 30, 31; Last revision: Penard 1912, Revue Suisse de Zoologie, 20, p. 9, Pl. 1, Figs 6–8.

Synonyms: Difflugia arcula Leidy, 1879; Cystidina arcula (Leidy, 1879) Volz, 1929.

Description: Shell yellow or brown, circular in apertural and aboral views, hemispherical in lateral view (Fig. 26 A-F); composed mainly of small to medium flattish partticles, embedded in deep layer of organic cement on the apertural side, large and rough pieces of quartz on the aboral side (Fig. 26 D-F). Organic cement with numerous small pores on the apertural and lateral surface (Fig. 26 D, I). Aperture usualy triangular or quadrangular, sometimes with irregular outline, central, invaginated, and surrounded by a small collar of orgenic cement (Fig. 26 D, G, H).

Ecology: In soils, mosses and forest litter, very rarely in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rila Mts. (Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990, Bankov et al. 2018).

Trigonopyxis arcula. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 99.9 97.0 9.05 1.51 9.05 86 133 36
Diameter of aperture 26.2 26.0 4.15 0.80 15.84 20 35 27
Depth 59.9 58.5 8.95 2.00 14.93 47 74 20
Depth/Diameter ratio 0.60 0.59 0.08 0.02 12.90 0.5 0.8 20
Aperture/Diameter ratio 0.26 0.26 0.03 0.006 12.47 0.2 0.3 27
Figure 26.

Light (A, C) and scanning electron (B, D-I) micrographs of Trigonopyxis arcula. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two specimens showing smooth apertural surface and characteristic triangular aperture. (E) Dorsal view. (F) Lateral view. (G, H) Close up views of aperture to illustrate its variability in shape. (I) Detail of apertural side to illustrate its smooth surface and numerous pores in the organic cement.

Difflugia acuminata Ehrenberg, 1838

Original description: Ehrenberg 1838, Die Infusionthierchen als vollkommene Organismen, p. 131, Taf. IX, fig. 3.

Synonyms: Difflugia curvicaulis Penard, 1899; Difflugia acuminata var. umbilicata Penard, 1902; Difflugia venusta Ogden, 1983

Description: Shell brown, opaque, cylindrical or elongate pyriforme, with a pointed or acuminate aboral region, circular in transverse section (Fig. 27 A-H); with rough surface and covered mainly of medium to large quartz particles, occasionally with fragment of diatom frustules (Fig. 27 B, C, E). Areas of organic cement usually well seen in the shell matrix as a network, the mesh of which about 1-1,2 μm in diameter and the walls about 180-250 nm thick, each mesh enclosure having a smaller network with a mesh about 100-150 nm in diameter (Fig. 27 I). Aperture circular, well defined; surrounding rim covered with a regularly arranged small particles or chrysomonad cysts (Fig. 27 E-G). Cytoplasm abundant, fulfilled with many granules, without symbiotic zoochlorellae; one large ovular nucleus and many nucleoli. Pseudopodia usually one or two, long and fast moving (Fig. 27 A, D).

Notes: The species has been recorded in both as nominal species and as synonym D. venusta (Rhodopes Mts.) .

Ecology: Frequent in freshwater habitats, less common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Bankov et al. 2018).

Difflugia acuminata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 248.8 230.7 49.44 5.95 19.87 169.5 346.0 69
Breadth 94.9 96.0 5.80 0.70 6.10 82.0 110.3 69
Diameter of aperture 45.6 45.0 6.71 0.81 14.72 30.6 62.1 69
Length of aboral horn 27.8 26.1 9.47 1.68 34.12 13.0 57.0 69
Breadth/Length ratio 0.39 0.41 0.07 0.009 17.93 0.3 0.5 69
Aperture/Breadth ratio 0.48 0.49 0.07 0.008 14.09 0.3 0.6 69
Figure 27.

Light (A, C, D) and scanning electron (B, E-I) micrographs of Difflugia acuminata. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, E) Lateral views of two specimens showing general shell shape. (D) View of live specimen to illustrate a single long endolobopodia. (F) Apertural view showing regular apertural outline. (G) Latero-apertural view to show apertural rim and surrounding, regularly arranged small particles (H) View of acuminate aboral region. (I) Detail of organic cement network.

Difflugia ampullula Playfair, 1918

Original description: Playfair 1918, Proceedings of the Linnean Society of New South Wales, 42, p. 650, Pl. XXXVII, fig. 10, 11.

Description: Shell transparent, ovoid, circular in transverse section, tapering evenly from the mid-body position towards the aperture and rounded aboral region (Fig. 28 A-D); composed mainly of small to medium pieces of quartz, so arranged to give a well defined and regular outline with a smooth surface (Fig. 28 C-F). Shell components usually in close contact with each other, only small areas of organic cement are visible between particles; cement in form of a network of small meshes of about 300-400 nm in diameter (Fig. 28 I). Aperture circular, well defined by the surrounding slightly raised collar of small particles (Fig. 28 E-H).

Ecology: Frequent in freshwater sediments, less common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Difflugia ampullula. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 80.2 80.0 3.28 0.60 4.08 75 88 30
Breadth 59.6 60.0 2.81 0.51 4.72 54 65 30
Diameter of aperture 22.6 23.0 1.76 0.32 7.78 18 26 30
Breadth/Length ratio 0.74 0.74 0.04 0.007 5.02 0.7 0.8 30
Aperture/Breadth ratio 0.38 0.38 0.03 0.006 8.22 0.3 0.4 30
Figure 28.

Light (A) and scanning electron (B-I) micrographs of Difflugia ampullula. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C-D) Lateral view of two specimens showing regular outline and smooth shell surface. (E-F) Latero-apertural view to illustrate small collar. (G) Apertural view to show irregular edge of the collar. (H) Lateral view of apertural region. (I) Portion of shell surface to show arrangement of particles and small areas of organic cement in form of a network of small meshes.

Difflugia bryophila (Penard, 1902) Jung, 1942

Original description: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 221, fig. 7 (p. 218); Last revision: Jung 1942, Archv für Protistenkdunde, 95, p. 275, Abb. 1.

Synonyms: Difflugia pyriformis var. bryophila Penard, 1902; Difflugia oblonga var. longicollis Gassowsky, 1936; Difflugia longicollis (Gassowsky, 1936) Ogden and Hedley, 1980; Difflugia gassowskii Ogden, 1983.

Description: Shell brown, opaque, pyriform, with sides tapering evenly to the aperture or forming a distinct short neck about one-third of the body length; rounded aboral region and circular transverse section (Fig. 29 A-D); rough, covered mainly of small to medium quartz particles, occasionally with fragment of diatom frustules or chrysomonad cysts (Fig. 29 C-H). Shell components usually in close contact with each other, only small areas of organic cement is seen infrequently as an open network; mesh about 500-750 μm in diameter, without well pronounced walls. Each mesh enclosure covered by inner strands of cement which form a smaller mesh with different size (Fig. 29 I). Aperture roughly circular, surrounding rim covered by small particles or flagellate cysts (Fig. 29 E-G). Cytoplasm abundant, fills almost whole shell, without symbiotic zoochlorellae; one large ovular nucleus and a few nucleoli (Fig. 29 A-B). Pseudopodia usually one or two, long, fast moving.

Notes: The species has been recorded in both as nominal species and as synonym D. gassowskii (Rhodopes Mts., Rila Mts., Vitosha Mts.).

Ecology: Frequent in freshwater habitats and in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Difflugia bryophila. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 129.4 129.1 10.54 1.89 8.15 109.9 148.8 31
Breadth 61.1 60.1 6.64 1.19 10.88 52.8 78.3 31
Diameter of aperture 25.6 25.4 2.90 0.52 11.30 21.1 31.3 31
Breadth/Length ratio 0.47 0.48 0.05 0.009 10.07 0.4 0.6 31
Aperture/Breadth ratio 0.42 0.44 0.06 0.010 13.12 0.3 0.5 31
Figure 29.

Light (A, B) and scanning electron (C-I) micrographs of Difflugia bryophila. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Lateral view showing rough surface of the shell. (E) Apertural view. (F) Close up view of aperture to show bordering particles. (G) Lateral view of apertural rim showing its irregularity (H) Portion of shell to show arrangement of particles and rough surface of the shell. (I) Detail of organic cement network.

Difflugia elegans Penard, 1890

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 140, Pl. IV, fig. 4 à 11.

Synonyms: Difflugia amphoralis Hopkinson, 1909; Difflugia australis (Playfair, 1918) Gauthier-Lièvre et Thomas, 1958; Difflugia borodini Gassowsky, 1936; Difflugia elegans f. bicornis Jung, 1936; Difflugia elegans f. tricornis Jung, 1936; Difflugia juzephiniensis Dekhtyar, 1993; Difflugia leidyi Wailes, 1912; Difflugia Solowetskii Mereschkowsky, 1877; Difflugia tricornis (Jung, 1936) Ogden, 1983; Difflugia varians Penard, 1902

Description: Shell yellowish-brownish, ovoid, with slightly pronounced neck near the aperture; aboral extremity tapering evenly to short tubular horn; uncompressed, with circular transverse section (Fig. 30 A-F); covered mainly of small to medium quartz particles, mixed with diatom frustules or chrysomonad cysts, with rough surface (Fig. 30 D-F). Small areas of organic cement usually well seen in shell matrix as a network, with mesh 300-450 nm in diameter and dividing walls about 150-280 nm thick (Fig. 30 I). Aperture circular, surrounded by irregularly arranged small particles, diatoms or chrysomonad cysts, often clogged with aggregation of quartz particles (Fig. 30 E-H). Cytoplasm granular, does not fills the whole shell, without symbiotic zoochlorellae; active amoebae infrequently seen, live specimens frequently encysted, cysts round, brown, with thick organic wall, occupying central region (Fig. 30 A). Pseudopodia numerous, thin, short, fast moving.

Notes: The species has been recorded in both as nominal species and as synonym D. amphoralis (Rila Mts., Vitosha Mts.).

Ecology: Frequent in freshwater habitats, as well as in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018) Vitosha Mts. (Pateff 1924, Golemansky 1965, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Difflugia elegans. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 107.0 106.8 11.21 1.95 10.48 81 128 33
Breadth 69.7 67.8 9.18 1.60 13.17 54 95 33
Diameter of aperture 30.6 30.0 5.07 0.88 16.57 22 41 33
Length of horn 15.6 14.9 7.70 1.68 49.40 4.4 39.6 21
Breadth/Length ratio 0.65 0.64 0.08 0.013 11.56 0.5 0.8 33
Aperture/Breadth ratio 0.44 0.44 0.08 0.014 18.03 0.3 0.6 33
Figure 30.

Light (A, C) and scanning electron (B, D-I) micrographs of Difflugia elegans. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C-E) Lateral view of three specimens. (F) View of specimen with clogged aperture. (G) Apertural view. (H) Lateral view of apertural region. (I) Detail of organic cement network.

Difflugia globulosa Dujardin, 1837

Original description: Dujardin 1837, Annales des sciences Naturelles, Zoologie, 8, p. 311, Pl. IX, fig. 1a, b.

Synonyms: Difflugia proteiformis Ehrenberg, 1838 subsp. globularis Wallich, 1864; Difflugia globularis (Wallich, 1864) Leidy, 1877; Difflugia chardezi Godeanu, 1972.

Description: Shell yellowish-brownish, opaque, circular in apertural and aboral views, spherical or hemispherical in lateral view (Fig. 31 A-F); composed mainly of small to medium pieces of quartz, mixed with diatom frustoles, with rough surface (Fig. 31 C-I). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 31 G- I). Aperture terminal, circular, central, surrounded by pieces of quartz (Fig. 31 C, D, G, H).

Ecology: Frequent in freshwater standing bodies, as well as in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005); Vitosha Mts. (Todorov 1993, Golemansky and Todorov 1985, 1990, Todorov and Golemansky 1995).

Difflugia globulosa. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 85.3 83.8 6.29 1.14 7.35 76 100 30
Depth 77.9 78.1 7.06 1.44 9.07 66 96 24
Diameter of aperture 36.9 36.9 3.30 0.60 8.94 31 44 30
Depth/Diameter ratio 0.92 0.93 0.05 0.01 5.93 0.8 1.0 24
Aperture/Diameter ratio 0.43 0.43 0.04 0.007 8.33 0.4 0.5 30
Figure 31.

Light (A) and scanning electron (B-I) micrographs of Difflugia globulosa. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C-D) Apertural view of two specimens showing general shape. (E) Dorsal view. (F) Lateral view. (G, H) Close up views of aperture to illustrate its rough rim and circular outline. (I) Detail of aboral side of the shell to illustrate its rough surface, covered with sand grains and diatom frustules.

Difflugia hiraethogii Ogden, 1983

Original description: Ogden 1983, Bulletin of the British Museum (Natural History), Zoology series, 44 (1), p. 59, Figs, 41, 42.

Description: Shell transparent or yellow, pyriform, rounded aborally and tapering towards the aperture forming a distinct short neck (Fig. 32 A-D); laterally compressed, except the neck region, with almost parallel sides, oval transverse section of the main body and circular neck (Fig. 32 E); composed mainly of flattish pieces of quartz, with a smooth appearance, except the neck region composed of angular qurtz and rough (Fig. 32 C-D, H). Organic cement in form of a network of fused rings, as a part of the shell matrix; rings with an internal diameter of about 300 nm and thickness of the wall of about 250 nm (Fig. 32 I). Aperture large, roughly circular, with irregular outline depending on the arrangement of the surrounding angular particles of quartz (Fig. 32 F-G). Cytoplasm abundant, without symbiotic zoochlorellae. Active amoebae infrequently seen, usually live specimens are encysted, cysts round, brown, with thick organic wall, occupying rounded aboral region (Fig. 32 A-B). Pseudopodia usually two-three, digitiform, slow moving.

Ecology: Frequent in Sphagnum.

Geographical distribution: Not well studied, probably cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Difflugia hiraethogii Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 207.1 206.0 20.90 3.48 10.09 174 254 36
Breadth 133.3 130.5 9.80 1.63 7.35 106 157 36
Diameter of aperture 61.5 58.4 9.20 1.53 14.98 52 86 36
Depth 90.1 89.0 7.59 1.28 8.42 81 118 35
Breadth/Length ratio 0.65 0.65 0.05 0.008 7.41 0.6 0.7 36
Aperture/Breadth ratio 0.46 0.44 0.05 0.008 11.06 0.4 0.6 36
Figure 32.

Light (A, B) and scanning electron (C-I) micrographs of Difflugia hiraethogii. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C, D) Broad lateral view of two individuals illustrating pyriform shape and distinct short neck. (E) Lateral view to show compression of the shell. (F) Apertural view (G) Close up view of aperture showing its irregular outline and surrounding angular particles of quartz. (H) Portion of shell to show arrangement of flattish particles to give a smooth surface. (I) Detail of organic cement network.

Difflugia lanceolata Penard, 1890

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 145, Pl. IV, fig. 59 à 60.

Description: Shell transparent, elongate, circular in transverse section, tapering from the widest diameter, situated usually at two-thirds of the shell length from the aperture, with rounded aboral region, rarely tapering at both ends (Fig. 33 A-F); smooth, thin, composed mainly of small to medium flattish pieces of quartz and occasional fragment of diatom frustules, so arranged to give a well defined and regular outline with surface appearing as though it is polished (Fig. 33 C-F). Shell components usually in close contact with each other, with only small areas of organic cement between them (Fig. 33 H). Cement as a network of small perforated rings about 350-500 nm in diameter; the perforation about 100-150 nm and wall about 150-300 nm in thickness (Fig. 33 I). Aperture circular, well defined, surrounding rim covered with a thin layer of organic cement (Fig. 33 G). Cytoplasm abundant, fulfilled with many brilliant, colorless granules, without symbiotic zoochlorellae; one large ovular nucleus, about 25-30 μm in diameter, many nucleoli. Pseudopodia usually one or two, long, fast moving (Fig. 33 I).

Ecology: Frequent in freshwater sediments, less common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990).

Difflugia lanceolata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 155.9 153.5 15.44 1.96 9.90 127 179 62
Breadth 66.7 66.0 5.14 0.65 7.71 58 77 62
Diameter of aperture 27.7 27.0 2.68 0.34 9.68 23 36 62
Breadth/Length ratio 0.43 0.42 0.02 0.003 4.65 0.39 0.49 62
Aperture/Breadth ratio 0.42 0.41 0.03 0.003 7.14 0.36 0.50 62
Figure 33.

Light (A, C) and scanning electron (B, D-I) micrographs of Difflugia lanceolata. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen to illustrate a single long endolobopodia. (D-F) View of three specimens to show variability of shell shape. (G) Apertural view showing aperture outline and thin organic collar. (H) Portion of shell to show arrangement of siliceous particles to give a smooth surface. (I) Detail of organic cement network.

Difflugia lobostoma Leidy, 1874

Original description: Leidy 1874a, Proceedings of the Academy of Natural Sciences of Philadelphia, 26, p. 79.

Description: Shell yellowish or brownish, opaque, circular in apertural and aboral views, spherical or hemispherical in lateral view (Fig. 34 A-F); composed mainly of small to medium pieces of quartz, with a rough surface (Fig. 34 D-I). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 34 G- I). Aperture terminal, tri- or four lobed, central, surrounded by collar of small pieces of quartz (Fig. 34 E-H). Cytoplasm abundant, with symbiotic zoochlorellae (Fig. 34 A). Pseudopodia numerous, long, thin, fast moving (Fig. 34 C).

Ecology: Frequent in freshwater standing bodies, accidentally in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006).

Difflugia lobostoma. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 173.9 173.0 12.16 2.22 6.99 150 198 30
Depth 166.3 161.5 12.41 2.27 7.46 147 191 30
Diameter of aperture 56.8 54.0 6.02 1.10 10.61 47 69 30
Depth/Diameter ratio 0.96 0.95 0.06 0.01 6.23 0.8 1.2 30
Aperture/Diameter ratio 0.33 0.32 0.02 0.003 5.75 0.3 0.4 30
Figure 34.

Light (A, C) and scanning electron (B, D-I) micrographs of Difflugia lobostoma. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen to illustrate numerous pseudopodia. (D) Lateral view. (E, F) Apertural view of two specimens showing general shape, as well as tri- and four lobed aperture. (G, H) Close up views of aperture to illustrate its rough rim and trilobed aperture. (I) Portion of shell to illustrate its rough surface, covered with sand grains.

Difflugia lucida Penard, 1890

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 145, Pl. IV, fig. 52 à 58

Description: Shell hyaline, ovoid, rounded aborally and tapering gradually towards the aperture (Fig. 35A-D); laterally strongly compressed, with elliptical transverse section (Fig. 35 F); composed mainly of flattish, not overlapping siliceous particles, so arranged to give it a smooth appearance (Fig. 35 D-I). Organic cement in the form of a network of rings, usually well seen as a part of the shell matrix; rings with internal diameter of about 400-500 nm and thickness of walls of about 100 nm (Fig. 35 I). Aperture elliptical, with irregular outline depending on arrangement of the surrounding flattish particles of quartz (Fig. 35 E, G). Cytoplasm abundant, fills most of the shell, without symbiotic zoochlorellae; one small ovular nucleus, about 10 μm in diameter, many nucleoli. Pseudopodia few, usually two or three, long, thin, fast moving.

Ecology: Frequent in mosses, soil and forest litter, as well as in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Difflugia lucida Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 73.5 73.2 4.62 0.82 6.29 65 83 32
Breadth 46.7 47.1 4.01 0.71 8.59 33 56 32
Large axis of aperture 29.2 29.5 4.12 0.73 14.08 20 41 32
Depth 30.5 30.8 3.78 0.81 12.38 22 36 22
Breadth/Length ratio 0.64 0.64 0.07 0.012 10.85 0.5 0.9 32
Aperture/Breadth ratio 0.63 0.63 0.06 0.011 10.30 0.5 0.8 32
Figure 35.

Light (A, C) and scanning electron (B, D-I) micrographs of Difflugia lucida. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Broad lateral view illustrating smooth shell surface. (E) Apertural view to show elliptical aperture. (F) Lateral view to show compression of the shell. (G) Broad lateral view of aperture to show surrounding and irregularly arranged particles of quartz, giving to it a rough outline. (H) Portion of shell to show arrangement of flattish particles to give a smooth surface. (I) Detail of organic cement network.

Difflugia oblonga Ehrenberg, 1831

Original description: Ehrenberg 1831, Abhandlungen der Königlichen Akademie der Wissenszchaften zu Berlin, 31, p. 90.

Synonyms: Difflugia bacillifera Penard, 1890; Difflugia lacustris (Penard, 1899) Ogden, 1983; Difflugia oblonga f. cyphodera Jung, 1942; Difflugia oblong a var. incondita Gauthier-Lièvre et Thomas, 1958; Difflugia oblonga var. lacustris Cash and Hopkinson, 1909; Difflugia oblonga var. parva Thomas, 1954; Difflugia parva (Thomas, 1954) Ogden, 1983; Difflugia pyriformis var. lacustris Penard, 1899

Description: Shell brown, opaque, pyriform, with sides tapering evenly to the aperture or forming a distinct neck about one-third of the body length, with rounded aboral region and circular transverse section (Fig. 36 A-E); covered mainly of medium to large quartz particles, rough (Fig. 36 B, E, H). Areas of organic cement usually well seen in the shell matrix as a network with open mesh having a diameter of 50-150 nm and dividing walls about 180-300 nm thick (Fig. 36 H, I). Aperture circular, surrounding rim covered by small particles (Fig. 36 F-H). Cytoplasm abundant, fills almost whole shell, without symbiotic zoochlorellae; one large ovular nucleus, numerous nucleoli. Pseudopodia usually one or two, long, fast moving. (Fig. 36 A, C, D).

Notes: Besides the nominal species, the synonyms D. parva (Rhodopes Mts., Rila Mts., Vitosha Mts.), D. lacustris (Rhodopes Mts., Vitosha Mts.), D. bacillifera (Rila Mts., Vitosha Mts.) and infrasubspecific taxa D. oblonga var. lacustris (Vitosha Mts.) and D. oblonga var. parva (Rila Mts., Vitosha Mts.) have also been recorded. According to us the synonymization of D. parva and D. bacillifera with D. oblonga needs confirmation with molecular methods.

Ecology: Frequent in freshwater habitats, as well as in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Difflugia oblonga. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 242.7 238.7 46.5 8.49 19.16 180 341 30
Breadth 130.4 121.6 30.4 5.55 12.3 94 199 30
Diameter of aperture 45.9 45.9 8.0 1.47 17.53 31 61 30
Breadth/Length ratio 0.54 0.54 0.05 0.01 10.01 0.4 0.6 30
Aperture/Breadth ratio 0.36 0.36 0.06 0.01 17.06 0.3 0.6 30
Figure 36.

Light (A, C, D) and scanning electron (B, E-I) micrographs of Difflugia oblonga. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C, D) View of two live specimens to illustrate a single long endolobopodia. (E) Lateral view. (F) Apertural view. (G) Close up view of aperture. (H) Portion of shell to show arrangement of particles and rough surface of the shell. (I) Detail of organic cement network.

Difflugia penardi Hopkinson, 1909

Original description: Cash and Hopkinson 1909. The British Freshwater Rhizopoda and Heliozoa. Vol. II, p. 14, Pl. XVIII, figs. 4-6.

Synonyms: Difflugia fallax Penard, 1890; Difflugia pyriformis var. tenuis Penard, 1890; Difflugia manicata Penard, 1902; Difflugia oblonga var. tenuis Wailes and Penard, 1911; Difflugia tenuis (Penard, 1890) Ogden, 1983.

Description: Shell yellow or brown, elongate or ovoid, with sides tapering evenly and gradually from rounded aboral region towards to aperture, circular in transverse section (Fig. 37 A-C); covered mainly of small to medium quartz particles, occasionally with fragment of diatom frustules or chrysomonad cysts, rough (Fig. 37 D-F). Shell components usually in close contact with each other, organic cement is seen infrequently (Fig. 37 I). Aperture small, circular, surrounding rim covered by small particles or flagellate cysts (Fig. 37 F-H). Cytoplasm not abundant, fills about half of the shell; fulfilled with brilliant, colorless granules, rarely has a few symbiotic zoochlorellae; one vesicular nucleus, about 12-15 μm in diameter, one central nucleolus. Pseudopodia usually two or three, long, thin, sometimes flattened and expanded, slow moving.

Notes: The species has been recorded in both as nominal species and as synonym Difflugia manicata (Rhodopes Mts., Rila Mts., Vitosha Mts.).

Ecology: Frequent in freshwater habitats and in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Difflugia penardi. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 83.0 81.0 7.90 1.37 9.51 74 101 33
Breadth 45.2 45.1 5.42 0.94 11.99 38 62 33
Diameter of aperture 22.9 21.5 4.95 0.86 21.7 15 37 33
Breadth/Length ratio 0.55 0.55 0.06 0.010 10.62 0.4 0.7 33
Aperture/Breadth ratio 0.50 0.50 0.10 0.018 20.03 0.3 0.8 33
Figure 37.

Light (A, B) and scanning electron (C-I) micrographs of Difflugia penardi. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D-E) Lateral view of two specimens showing rough surface of the shell. (F) Latero-apertural view. (G) Apertural view. (H) Close up view of aperture to show bordering small particles. (I) Portion of shell to illustrate arrangement of particles and rough surface of the shell.

Difflugia pulex Penard, 1902

Original description: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 229, fig. 1 à 8 (p. 230).

Synonyms: Difflugia minuta var. minor Godeanu, 1972; Difflugia ovalisina Beyens et Chardez, 1994.

Description: Shell transparent, ovoid, circular in transverse section, tapering evenly from the mid-body position towards the aperture, with rounded aboral region (Fig. 38 A-F); composed of small to medium flattish pieces of quartz, mixed with pieces of diatom frustules, with rough surface (Fig. 38 A-F). Shell components usually in close contact with each other; only small areas of organic cement with single small pores are visible between particles (Fig. 38 H, I). Aperture circular, with irregular outline, surrounded by quartz particles of different size (Fig. 38 F, G).

Ecology: Frequent in freshwater sediments and in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Pateff 1924, Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky and Todorov 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Difflugia pulex. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 38.1 38.7 3.81 0.95 10.00 27 43 16
Width 27.4 27.9 4.26 1.06 15.56 17 36 16
Aperture diameter 12.9 13.7 1.69 0.42 13.05 10 15 16
Width/Length ratio 0.72 0.73 0.08 0.02 11.67 0.6 0.9 16
Aperture diameter/Width ratio 0.48 0.48 0.06 0.02 12.85 0.4 0.6 16
Figure 38.

Scanning electron micrographs of Difflugia pulex. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C-E) Lateral view of three specimens showing different shape and shell structure. (F) Latero-apertural view. (G) Apertural view to show its irregular edge. (H, I) Portion of shell surface to show arrangement of flattish particles and small areas of organic cement with single small pores.

Difflugia pyriformis Perty, 1849

Original description: Perty 1849, Mittheilungen der Naturforschenden Gesellschaft in Bern, no 164-165, p. 168.

Description: Shell brown, opaque, pyriform, with sides tapering evenly to the aperture or forming a distinct neck about one-third of the body length; rounded aboral region and circular transverse section (Fig. 39 A-F); rough, covered mainly of medium to large quartz particles (Fig. 39 D-F). Areas of organic cement are usually well seen in the shell matrix as a network with the open mesh having a diameter of 50-150 nm and dividing walls about 150-300 nm thick (Fig. 39 I). Aperture circular, surrounding rim covered by small particles (Fig. 39 F, G). Cytoplasm abundant, fills the whole shell, fulfilled with numerous symbiotic zoochlorellae; one large ovular nucleus, numerous nucleoli. Pseudopodia usually one or two, long, fast moving. (Fig. 39 A, C).

Ecology: Frequent in freshwater standing bodies, accidentally in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Pateff 1924); Rila Mts. (Pateff 1924); Vitosha Mts. (Pateff 1924).

Difflugia pyriformis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 342.2 344.7 20.18 3.19 5.90 297 383 40
Width 195.9 196.6 13.09 2.07 6.68 152 225 40
Aperture diameter 64.6 63.6 7.20 1.14 11.15 47 78 40
Width/Length ratio 0.57 0.58 0.04 0.007 7.83 0.4 0.7 40
Aperture diameter/Width ratio 0.33 0.32 0.04 0.006 11.89 0.3 0.4 40
Figure 39.

Light (A, C) and scanning electron (B, D-I) micrographs of Difflugia pyriformis. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen to illustrate a single long endolobopodia and granular cytoplasm with symbiotic zoochlorelae. (D, E) Lateral views of two individuals to show general shape. (F) Apertural view. (G) Close up view of aperture showing its circular outline and surrounding small particles of quartz. (H) Portion of shell to show arrangement of particles and rough surface of the shell. (I) Detail of organic cement network.

Difflugia rubescens Penard, 1891

Original description: Penard 1891b, The American Naturalist, 25, p. 1075.

Description: Shell yellow or brown, transparent, pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture, circular in transverse section (Fig. 40 A-E); rough, covered mainly of small to medium quartz particles usually mixed with fragments of diatom frustules or chrysomonad cysts (Fig. 40 D-F). Shell components usually in close contact with each other, organic cement visible infrequently (Fig. 40 I). Aperture roughly circular, bordered by an organic collar with crenulated inner margin and forming tooth-like structures (Fig. 40 F-H). Cytoplasm not abundant, fills about half of the shell, fulfilled with many orange-red colored granules; one vesicular nucleus about 10 μm in diameter, one small central nucleolus. Active amoebae infrequently seen, usually live specimens are encysted, cysts round, brown, with thick organic wall, occupying rounded aboral region. Pseudopodia usually one or two, short, digitiform, sometimes flattened, slow moving.

Ecology: Frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rila Mts. (Pateff 1924, Golemansky and Todorov 1993, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Difflugia rubescens. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 72.7 71.1 7.50 1.22 10.31 56 91 38
Breadth 45.4 46.2 5.73 0.93 12.63 32 59 38
Diameter of aperture 20.1 20.5 3.62 0.59 18.02 13 27 38
Breadth/Length ratio 0.63 0.63 0.07 0.012 11.46 0.5 0.7 38
Aperture/Breadth ratio 0.44 0.45 0.06 0.010 13.33 0.3 0.5 38
Figure 40.

Light (A, C) and scanning electron (B, D-I) micrographs of Difflugia rubescens. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C) View of encysted specimen. (D-E) Lateral view of two specimens to illustrate rough surface of the shell. (F) Apertural view. (G-H) Close up view of aperture showing the bordering crenulated organic collar. (I) Portion of shell to show arrangement of particles and rough surface of the shell.

Difflugia urceolata Carter, 1864

Original description: Carter 1864, Annals and Magazine of Natural History, 13, p. 27, Pl. I, fig. 7.

Synonyms: Difflugia urceolata var. olla Leidy, 1879; Difflugia urceolata var. sphaerica Playfair, 1917.

Description: Shell large, opaque, ovoid or circular, sometimes with irregular aboral protruberances and a pronounced thick apical collar (Fig. 41 A-E); composed of a mixture of small and large pieces of quartz, so arranged to give it a relatively smooth and regular outline (Fig. 41 A-E). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 41 I). Aperture circular, well defined, with reqular outline, surrounded by a collar made of small quartz particles (Fig. 41 C, E-H). Cytoplasm not abundant, fills about half of the shell, usually fulfilled with green algae. Multinucleate, about 50 or more nuclei, each of them with many nucleoli. Pseudopodia numerous, long, thin, fast moving.

Ecology: Common in freshwater sediments, incidentally in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006).

Difflugia urceolata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 295.0 296.2 33.60 5.68 11.39 219 378 35
Breadth 253.7 244.7 37.71 6.37 14.86 176 342 35
Diameter of aperture 161.5 156.0 15.96 2.70 9.89 133 186 35
Breadth/Length ratio 0.86 0.85 0.07 0.01 7.70 0.75 0.98 35
Aperture/Breadth ratio 0.65 0.65 0.1 0.02 15.97 0.4 0.9 35
Figure 41.

Light (A, B) and scanning electron (C-I) micrographs of Difflugia urceolata. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Lateral view. (E) Latero-apertural view. (F) Apertural view. (G) Close up view of aperture to show its regular outline. (H) Lateral view of apertural region to illustrate the surrounding collar made of small quartz particles. (I) Portion of shell to show arrangement of particles and rough surface of the shell.

Difflugia viscidula Penard, 1902

Original description: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 259, fig. 1 à 4 (p. 260).

Synonyms: Difflugia lemani Blanc, 1892; Difflugia histrio Penard, 1908; Difflugia lemani var. palustris Chardez, 1956; Difflugia lebes var. masurica Schönborn, 1965; Difflugia lebes var. bretschkoi Laminger, 1971; Difflugia finstertaliensis Laminger, 1971.

Description: Shell large, opaque, ovoid, circular in transverse section, tapering evenly from the mid-body position towards the aperture, with rounded aboral region (Fig. 42 A-E); composed of a mixture of small and large pieces of quartz, rarely included diatom frustules (Fig. 42 A-E). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 42 I). Aperture circular, well defined, with reqular outline, surrounded by small particles (Fig. 42 E-H). Cytoplasm does not fills the whole shell, usually fulfilled with brown granules (Fig. 42 A, C, D); one large ovular nucleus with many nucleoli. Pseudopodia few, short, thin, very slow moving, rarely visible; sometimes large part of cytoplasm protrude out from the aperture forming flattened, fan-shaped disc with short pseudopodia, adhered to the substrate (Fig. 42 C, D).

Notes: The species has been recorded as nominal species, as synonym D. lemani, as infrasubspecific taxon D. lemani var. palustris and as Difflugia sp. (Vitosha Mts.).

Ecology: Common in freshwater sediments, less frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Vitosha Mts. (Pateff 1928, Golemansky 1965, Golemansky and Todorov 1985, 1990).

Difflugia viscidula. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 230.9 228.7 15.18 2.77 6.57 200 267 30
Breadth 171.2 170.0 12.16 2.22 7.10 149 204 30
Diameter of aperture 86.1 86.0 14.44 2.64 16.78 64 108 30
Breadth/Length ratio 0.74 0.75 0.06 0.01 8.72 0.6 0.9 30
Aperture/Breadth ratio 0.50 0.51 0.08 0.01 15.87 0.4 0.6 30
Figure 42.

Light (A, C, D) and scanning electron (B, E-I) micrographs of Difflugia viscidula. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C-D) Lateral view of two live specimens showing different types of pseudopodia. (E) Lateral view. (F) Apertural view. (G) Close up view of aperture to show its regular outline. (H) Lateral view of apertural region. (I) Portion of shell to show arrangement of particles and rough surface of the shell.

Lesquereusia epistomium Penard, 1902

Original description: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 331, fig. 1 à 3.

Description: Shell colourless, transparent, consists of two parts, an ovoid or globular body and an oblique, long neck, clearly separated from each other with deep groove (Fig. 43 A-D); main body almost uncompressed laterally, with circular or oval transverse section; neck uncompressed with a circular aperture (Fig. 43 D-F); composed of characteristic siliceous vermiform rods, adhering at their edges but do not overlapping (Fig. 43 D-G); rods embedded by a network of organic cement with rosette-like pattern and meshes of about 600-800 nm in diameter; each mesh possess internal small network with irregular pores of about 60-140 nm (Fig. 43 H-I). Aperture circular, surrounded by siliceous rods, without organic collar (Fig. 43 D-F). Cytoplasm fulfilled with numerous brown granules, does not fills the whole shell; one large ovular nucleus with numerous small nucleoli; pseudopodia usually one or two, large, long and fast moving (Fig. 43 A, C).

Synonyms: Lecquereusia jurassica var. epistomium Penard, 1893; Lecquereusia epistomium Penard, 1902.

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Lesquereusia epistomium. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 122.0 121.4 6.94 1.25 5.69 104 138 31
Breadth 86.5 85.9 7.42 1.35 8.58 72 105 30
Diameter of aperture 23.3 22.6 3.57 0.65 15.30 19 33 30
Depth 73.1 72.0 5.02 1.26 6.87 66 86 16
Breadth/Length ratio 0.71 0.70 0.04 0.008 6.14 0.6 0.8 29
Aperture/Breadth ratio 0.27 0.26 0.04 0.007 14.35 0.2 0.4 30
Figure 43.

Light (A, C) and scanning electron (B, D-I) micrographs of Lesquereusia epistomium. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen to illustrate granular cytoplasm and long pseudopodia. (D) Broad lateral view to show general shape. (E) Narrow lateral view to illustrate clear distinction between body and neck. (F) Lateral view of apertural region. (G) Detail of shell surface showing shape and arrangement of siliceous curved rods. (H, I) Close up view of network of organic cement and porous structure of meshes.

Lesquereusia gibbosa Thomas and Gauthier-Lièvre, 1859

Original description: Thomas and Gauthier-Lièvre 1959b, Bulletin de la Société d’Histoire Naturelle de l’Afrique du Nord, 50, p. 44, Fig. 6 a, b, c, Pl. I – 31.

Description: Shell colourless, transparent, unsymmetrically-ovoid or pyriforme, with globular body and an oblique neck, clearly separated from the body with deep ventral groove and well-expressed fold of the dorsal side, forming an internal opening (Fig. 44 A-D); main body slightly compressed laterally, with oval transverse section; neck uncompressed, with circular aperture (Fig. 44 F, G); composed of characteristic siliceous vermiform rods, sometimes mixed with single sand grains; all particles adhering at their edges, do not overlap, embedded by a network of organic cement with a distinctive rosette-like pattern; meshes of about 500-800 nm in diameter; each mesh has an internal small network with irregular pores of about 80-100 nm (Fig. 44 D-I). Aperture circular, surrounded by siliceous rods, without organic collar (Fig. 44 D-G). Cytoplasm fulfilled with numerous brown granules, does not fills the whole shell; one large ovular nucleus with numerous small nucleoli; pseudopodia usually two or three, large, long, fast moving (Fig. 44 A, C).

Notes: Lesquereusia gibbosa differs from L. spiralis by its larger size, shorter and voluminous rods, structure of meshes of the organic cement and presence of a well-expressed fold of the dorsal side.

Ecology: In Sphagnum, less frequent.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky and Todorov 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Lesquereusia gibbosa. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 149.2 148.4 11.72 1.95 7.85 131 188 36
Breadth 125.5 125.0 10.21 1.86 8.14 96 140 30
Diameter of aperture 31.3 32.0 3.81 0.63 12.17 20 39 37
Depth 95.9 96.2 7.73 2.07 8.06 74 110 14
Breadth/Length ratio 0.84 0.84 0.05 0.008 5.38 0.72 0.95 30
Aperture/Breadth ratio 0.25 0.25 0.03 0.006 12.03 0.2 0.3 29
Figure 44.

Light (A, C) and scanning electron (B, D-I) micrographs of Lesquereusia gibbosa. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing granular cytoplasm and long pseudopodia. (D, E) Broad lateral view of two individuals to show general shape. (F) Narrow lateral view. (G) Apertural view. (H) Detail of shell surface showing shape and arrangement of siliceous curved rods and network of organic cement. (I) Close up view of a network of organic cement.

Lesquereusia modesta Rhumbler, 1896

Original description: Rhumbler 1896, Zeitschrift für Wissenschaftliche Zoologie, 61 (1), p. 101, Pl. IV, fig. 2.

Synonyms: Difflugia spiralis Leidy, 1879 (in part).

Description: Shell colourless, unsymmetrically-ovoid or circular, with globular body and short, oblique neck, separated with groove (Fig. 45 A-D); main body compressed laterally, with oval transverse section; neck uncompressed, with circular aperture (Fig. 45 C-E); composed mainly of small to medium grains of quartz mixed with a small number of siliceous vermiform rods (Fig. 45 C-G). Structural particles embedded by network of organic cement with a distinctive rosette-like pattern; meshes of about 500-600 nm in diameter; each mesh has an internal small network with twelve to eighteen irregular oppenings of about 70-150 nm (Fig. 45 G-I). Aperture circular, denticulate, surrounded by small particles of quartz, without organic collar (Fig. 45 D-F). Cytoplasm dark, fulfilled with brown granules, does not fills the whole shell; one large ovular nucleus with numerous nucleoli; pseudopodia usually one or two, large, long, fast moving.

Notes: Lesquereusia modesta is similar to L. spiralis by shell shape and size, but clearly differs from it by structure of the shell, which is rough and composed mainly of small to medium pieces of quartz.

Ecology: In standing freshwater basins, less frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Lesquereusia modesta. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 126.2 125.9 8.14 1.40 6.45 111 144 34
Breadth 104.0 102.5 9.57 1.75 9.20 85 120 30
Diameter of aperture 30.2 29.8 4.39 0.76 14.56 23 38 33
Depth 87.7 86.5 6.51 1.53 7.42 76 99 18
Breadth/Length ratio 0.82 0.82 0.05 0.009 6.22 0.7 0.9 30
Aperture/Breadth ratio 0.29 0.29 0.04 0.007 12.62 0.2 0.4 30
Figure 45.

Light (A, B) and scanning electron (C-I) micrographs of Lesquereusia modesta. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Broad lateral view. (E) Narrow lateral view. (F) Close up view of aperture showing its circular outline and bordering small particles of quartz. (G) Detail of shell surface showing shape and arrangement of sand grains of quartz. (H, I) Close up view of a network of organic cement and porous structure of meshes.

Lesquereusia spiralis (Ehrenberg, 1840) Bütschli, 1880

Original description: Ehrenberg 1840, Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königliche Preussischen Akademie der Wissenschaften zu Berlin, 5, p. 199; Last revision: Bütschli 1880, Protozoa. In: Bronn’s Their-Reichs, I, 1, Taf. III, fig. 9.

Synonyms: Difflugia spiralis Ehrenberg, 1840; Lecquereusia jurassica Schlumberger, 1845; Difflugia helix Cohn, 1853.

Description: Shell colourless, transparent, unsymmetrically-ovoid or pyriforme, with globular body and short, oblique neck, separated with deep groove (Fig. 46 A-D); main body compressed laterally, with oval transverse section; neck uncompressed, with circular aperture (Fig. 46 E-G); composed of characteristic siliceous vermiform rods, adhering at their edges, non-overlapping, embedded by network of organic cement with a distinctive rosette-like pattern; meshes of about 400-500 nm in diameter; each mesh has an internal small network with eight to ten pores of about 30-50 nm (Fig. 46 D-I). Aperture circular, surrounded by siliceous rods, without organic collar (Fig. 46 F-H). Cytoplasm fulfilled with brown granules, does not fills the whole shell; one large ovular nucleus with numerous small nucleoli; pseudopodia usually one or two, large, long, fast moving (Fig. 46 A, C).

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Lesquereusia spiralis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 114.7 113.5 8.81 1.53 7.68 102 146 33
Breadth 96.8 97.4 7.18 1.29 7.42 82 121 31
Diameter of aperture 25.9 26.0 2.35 0.41 9.05 21 32 33
Depth 72.0 71.9 5.62 1.40 7.81 63 90 16
Breadth/Length ratio 0.85 0.84 0.05 0.01 6.38 0.75 0.96 31
Aperture/Breadth ratio 0.27 0.27 0.02 0.004 7.51 0.2 0.3 31
Figure 46.

Light (A, C) and scanning electron (B, D-I) micrographs of Lesquereusia spiralis. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing granular cytoplasm and pseudopodia. (D) Broad lateral view. (E) Narrow lateral view. (F) Apertural view (G) Close up view of aperture to show its circular outline and bordering siliceous rods. (H) Lateral view of apertural region. (I) Detail of shell surface showing shape and arrangement of siliceous curved rods and network of organic cement.

Centropyxis aculeata (Ehrenberg, 1830) Stein, 1857

Original description: Ehrenberg 1830, Abhandlungen der Königlichen Akademie der Wissenszchaften zu Berlin, p. 40; Last revision: Stein 1857, Abhandlungen der Königlich Böhmischen Gesellschaft der Wissenschaften, 10, p. 43.

Synonyms: Arcella aculeata Ehrenberg, 1830; Difflugia aculeata Perty, 1852; Echinopyxis aculeata Claparède et Lachmann, 1859.

Description: Shell yellowish-brownish, ovoid or circular, usually with about four to eight lateral spines (Fig. 47 A-F); main body spherical in lateral view and tappers towards the aperture (Fig. 47 F); composed of small sand grains and diatom frustules, with rough surface; only the region around the aperture is smooth and covered mainly of organic cement (Fig. 47 C, D, G). Aperture large, circular or oval, invaginated and sub-terminal (Fig. 47 A-D).

Notes: Besides the nominal species two infrasubspecific taxa Centropyxis aculeata var. oblonga Deflandre, 1929 and Centropyxis aculeata var. grandis Deflandre, 1929 have also been recorded.

Ecology: Common in Sphagnum and standing freshwater bodies, among submerged aquatic vegetation.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, 2004, 2005, Todorov and Golemansky 1995, Bankov et al. 2018).

Centropyxis aculeata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 128.1 126.7 14.22 2.60 11.10 98 165 30
Breadth 94.0 96.1 19.41 3.54 20.64 58 133 30
Diameter of aperture 45.8 46.3 7.08 1.29 15.47 33 58 30
Depth 60.9 61.6 7.40 2.05 12.15 48 78 13
Spines 24.0 23.1 6.88 1.26 28.72 10 35 30
Breadth/Length ratio 0.73 0.73 0.1 0.02 15.13 0.50 0.99 30
Aperture/Breadth ratio 0.50 0.48 0.08 0.02 16.98 0.3 0.7 30
Figure 47.

Light (A) and scanning electron (B-I) micrographs of Centropyxis aculeata. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two specimens to illustrate general shape and shell structure. (E) Aboral view. (F) Lateral view. (G) Close up view of aperture to illustrate its circular shape and smooth surface around the aperture. (H, I) Details of posterior end of the shell to illustrate its rough surface, covered with sand grains and diatom frustules.

Centropyxis aerophila Deflandre, 1929

Original description: Deflandre 1929, Archiv für Protistenkunde, 67, p. 330, fig. 11 à 21.

Synonyms: Difflugia constricta Ehrenberg, 1838; Arcella arctiscon Ehrenberg, 1854.

Description: Shell yellowish-brownish, ovoid, considerably flattened in the apertural region (Fig. 48 A-E); main body spherical in lateral view and tappers towards the aperture to form an apertural rim (Fig. 48 F); shell with rough surface, composed of small to medium extraneous particles; only the region around the aperture is smooth and covered mainly of organic cement (Fig. 48 G, H). Aperture large, oval, invaginated and sub-terminal (Fig. 48 D, G, H).

Notes: Besides the nominal species, the infrasubspecific taxon Centropyxis aerophila var. sphagnicola Deflandre, 1929 has also been recorded (Rila Mts., Vitosha Mts.).

Ecology: Ubiquitous.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, 2004, 2005, Todorov and Golemansky 1995, Bankov et al. 2018).

Centropyxis aerophila. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 70.0 69.0 6.76 1.21 9.66 59 86 31
Breadth 57.6 56.2 5.85 1.05 10.15 49 72 31
Large axis of aperture 30.3 30.8 4.73 0.85 15.62 22 39 31
Depth 42.8 40.7 5.92 1.21 13.83 37 59 24
Breadth/Length ratio 0.82 0.82 0.05 0.01 6.44 0.7 0.9 31
Aperture/Breadth ratio 0.53 0.53 0.07 0.01 13.3 0.4 0.7 31
Figure 48.

Light (A, B) and scanning electron (C-I) micrographs of Centropyxis aerophila. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Apertural view to illustrate general shape and shell structure. (E) Dorsal view. (F) Lateral view. (G, H) Close up view of aperture to illustrate its oval shape and smooth surface around the aperture. (I) Detail of dorsal side to illustrate its rough surface, covered with small to medium sand grains.

Centropyxis cassis (Wallich, 1864) Deflandre, 1929

Original description: Wallich 1864, Annals and Magazine of Natural History, 13, p. 240-241, Pl. XV, Fig. 5b & 5c, Pl. XVI, Fig. 6; Last revision: Deflandre 1929, Archiv für Protistenkunde, 67, p. 335, fig. 35 à 40 (p. 336).

Synonyms: Difflugia cassis Wallich, 1864.

Description: Shell yellowish-brownish, roughly ovoid, with almost parallel sides and rounded edges (Fig. 49 A-D); main body spherical in lateral view and tappers gradually towards the aperture, without forming clear distinction between body and apertural rim (Fig. 49 F, F); with rough surface and composed of small to medium extraneous particles; only the region around the aperture is smooth and covered mainly of flattish particles embedded in a thick layer of organic cement (Fig. 49 B-I). Aperture large, oval, invaginated and sub-terminal (Fig. 49 B, C, G).

Ecology: Ubiquitous.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov 2004, 2005, Todorov and Golemansky 2000, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Centropyxis cassis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 68.0 66.9 5.90 1.08 8.67 60 82 30
Breadth 54.6 52.5 5.80 1.06 10.62 47 68 30
Large axis of aperture 30.4 29.4 4.50 0.82 14.79 24 41 30
Depth 42.2 39.7 7.72 2.06 18.28 32 58 14
Breadth/Length ratio 0.80 0.81 0.04 0.008 5.28 0.7 0.9 30
Aperture/Breadth ratio 0.56 0.55 0.04 0.008 7.87 0.5 0.7 30
Figure 49.

Scanning electron micrographs of Centropyxis cassis. (A) View of many specimens showing variability in shape and size of the shell. (B, C) Apertural view of two specimens to illustrate general shape and shell structure. (D) Dorsal view. (E) Latero-apertural view. (F) Latero-dorsal view. (G) Close up view of aperture to illustrate its oval shape and smooth surface around the aperture. (H) Detail of apertural side to illustrate its smooth surface. (I) Detail of dorsal side to illustrate its rough surface, covered with small to medium sand grains.

Centropyxis constricta (Ehrenberg, 1841) Penard, 1902

Original description: Ehrenberg 1841, Abhandlungen der Königliche Akademie der Wissenschaften zu Berlin, p. 410, Taf. IV, I-New York, Fig. 35, V-Kotzebue’s Sund, Fig. 1; Last revision: Penard 1902, Faune Rhizopodique du Bassin du Léman, pp. 298-301, fig. 1, 2.

Synonyms: Arcella constricta Ehrenberg, 1841; Difflugia constricta Leidy, 1879 (in part).

Description: Shell yellowish-brownish, elongated-ovoid, rounded posteriorly and tapered gradually towards the aperture (Fig. 50 A-D); main body spherical in lateral view, flattened slyghtly towards the aperture, without forming clear distinction between body and apertural rim (Fig. 50 C-F); with rough surface and composed of small to medium extraneous particles; usually with a few large quartz particles on the posterior apex; region around the aperture smooth and covered mainly of flattish particles embedded in a thick layer of organic cement (Fig. 50 C-I). Aperture large, oval, invaginated and sub-terminal (Fig. 50 C, D, G).

Ecology: Frequent in mosses, forest litter and soils, rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1990, Bankov et al. 2018).

Centropyxis constricta. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 107.0 106.0 9.94 1.68 9.30 87 126 35
Breadth 74.3 74.8 4.63 0.83 6.23 65 88 31
Large axis of aperture 38.7 39.6 4.40 0.82 11.37 30 50 29
Depth 70.5 71.0 7.85 1.96 11.14 46 80 16
Breadth/Length ratio 0.69 0.70 0.05 0.009 7.38 0.6 0.8 31
Aperture/Breadth ratio 0.52 0.53 0.06 0.01 11.24 0.4 0.7 29
Figure 50.

Light (A, B) and scanning electron (C-I) micrographs of Centropyxis constricta. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Apertural view to illustrate general shape and shell structure. (E) Latero-apertural view. (F) Latero-dorsal view. (G) Close up view of aperture to show its oval shape and smooth surface around the aperture. (H) Detail of apertural side showing its smooth surface. (I) Detail of dorsal side to illustrate its rough surface, covered with small to medium sand grains.

Centropyxis discoides (Penard, 1890) Deflandre, 1929

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 150, Pl. V, fig. 38 à 41; Last revision: Deflandre 1929, Archiv für Protistenkunde, 67, p. 351, fig. 104 à 107.

Synonyms: Centropyxis aculeata var. discoides Penard, 1890

Description: Shell yellow or brown, circular and usually with numerous spines on the lateral margins (Fig. 51 A-F); in lateral view considerably compressed, discoid (Fig. 51 B, F); with smooth apertural surface and rough dorsal surface; composed of sand grains mixed with diatom frustules; region around the aperture covered mainly of flattish particles embedded in a thick layer of organic cement (Fig. 51 D-I). Aperture large, invaginated, circular, central or subcentral (Fig. 51 A-D).

Ecology: Common in Sphagnum and standing freshwater bodies, among submerged aquatic vegetation.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990, Bankov et al. 2018).

Centropyxis discoides. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 168.5 164.7 16.68 2.95 9.90 141 207 32
Diameter of aperture 54.1 51.6 10.28 1.82 19.02 36 76 32
Depth 67.2 66.4 11.19 2.50 16.65 51 95 20
Spines 17.3 17.1 5.71 1.04 32.94 8 36 30
Aperture/Diameter ratio 0.31 0.31 0.04 0.007 13.15 0.3 0.4 32
Depth/Diameter ratio 0.39 0.39 0.07 0.02 17.19 0.2 0.5 20
Figure 51.

Light (A, C) and scanning electron (B, D-I) micrographs of Centropyxis discoides. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two specimens to illustrate general shape and shell structure. (E) Dorsal view. (F) Lateral view. (G) Close up view showing smooth apertural surface and disposition of spines on the lateral margin. (H) Close up view of a single spine to show its structure. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered with sand grains and diatom frustules.

Centropyxis ecornis (Ehrenberg, 1841) Leidy, 1879

Original description: Ehrenberg 1841, Abhandlungen der Königliche Akademie der Wissenschaften zu Berlin, p. 410, Taf. III, I-Real del monte, Fig. 46; Last revision: Leidy 1879, Report of the United States Geological Survey of the Territories, 12, p. 181, Pl. XXX, figs. 20-34, Pl. XXXI, figs. 33, 34, Pl. XXXII, figs. 35, 36.

Synonyms: Arcella ecornis Ehrenberg, 1841.

Description: Shell yellow or brown, circular (Fig. 52 A-E); in lateral view compressed; aboral region sub-spherical and tapers slightly to the apertural rim (Fig. 52 F); with smooth apertural surface and rough dorsal surface; composed of sand grains mixed with diatom frustules; region around the aperture covered mainly of flattish particles embedded in a thick layer of organic cement (Fig. 52 G, H). Aperture large, invaginated, oval or circular, sometimes with irregular outline, sub-terminal (Fig. 52 A-D, G).

Ecology: Frequent in Sphagnum and standing freshwater bodies.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Centropyxis ecornis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 137.7 138.3 9.96 1.73 7.23 122 154 33
Diameter of aperture 63.7 63.2 7.69 1.40 12.07 50 83 30
Depth 73.7 76.4 7.67 2.31 10.40 55 81 11
Aperture/Diameter ratio 0.46 0.46 0.04 0.008 9.48 0.4 0.6 30
Depth/Diameter ratio 0.52 0.53 0.06 0.02 10.33 0.4 0.6 11
Figure 52.

Light (A) and scanning electron (B-I) micrographs of Centropyxis ecornis. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two specimens showing general shape and shell structure. (E) Dorsal view. (F) Lateral view. (G) Close up view of aperture to show its irregular outline. (H) Detail of smooth apertural surface. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered with sand grains.

Centropyxis elongata (Penard, 1890) Thomas, 1959

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 149, Pl. V, fig. 17-20; Last revision: Thomas 1959, Procès-Verbaux de la Société Linneénne de Bordeaux, 97, p. 35, Pl. II, fig. 22-26, 28-31, 34.

Synonyms: Difflugia constricta var. elongata Penard, 1890.

Description: Shell yellow or brown, elongate (Fig. 53 A-E); in lateral view rounded, sub-spherical in the aboral region and considerably compressed in the apertural region (Fig. 53 F); with smooth apertural surface and rough dorsal surface; composed of flattish pieces of quartz occasionally mixed with diatom frustules; region around the aperture covered mainly of flattish particles embedded in a thick layer of organic cement (Fig. 53 C-I). Aperture large, invaginated, oval or circular, sub-terminal (Fig. 53 B-D, G).

Notes: C. elongata is similar to C. platystoma but differs from it by the more elongated and flattened shell as well as by the absence of a sharp border between the main body and the visor when viewed laterally.

Ecology: Frequent in mosses, forest litter and soils, rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Bankov et al. 2018); Vitosha Mts. (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995).

Centropyxis elongata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 68.2 69.2 6.59 0.95 9.67 64 81 48
Breadth 38.7 40.3 4.94 0.71 12.76 22 46 48
Diameter of aperture 23.1 22.8 3.12 0.45 13.53 16 30 48
Depth 33.4 34.1 3.98 0.64 11.90 27 41 39
Breadth/Length ratio 0.57 0.57 0.06 0.009 10.71 0.3 0.7 48
Aperture/Breadth ratio 0.60 0.60 0.08 0.01 13.18 0.5 0.96 48
Figure 53.

Light (A) and scanning electron (B-I) micrographs of Centropyxis elongata. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two specimens to show general shape and shell structure. (E) Dorsal view. (F) Lateral view. (G) Close up view of aperture. (H) Detail of smooth apertural surface. (I) Detail of aboral side of the shell to illustrate its rough surface, covered with flattish particles.

Centropyxis gibba Deflandre, 1929

Original description: Deflandre 1929, Archiv für Protistenkunde, 67, p. 357, fig. 118 à 120.

Description: Shell colorless or yellowish, ovoid or circular, usually with about four to eight lateral spines (Fig. 54 A-F); main body spherical in lateral view and considerably compressed towards the aperture (Fig. 54 F); with rough surface, composed mainly of diatom frustules; region around the aperture smooth and covered mainly of organic cement (Fig. 54 C-I). Aperture large, circular or oval, invaginated and sub-terminal (Fig. 54 C-D, G).

Ecology: In Sphagnum and standing freshwater bodies, among submerged aquatic vegetation, very rare.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov 2005).

Centropyxis gibba. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 127.0 126.2 13.22 2.34 10.41 105 152 32
Breadth 92.8 90.0 9.83 1.77 10.60 74 116 31
Diameter of aperture 48.9 48.3 5.93 1.05 12.11 37 63 32
Depth 77.6 80.6 9.55 2.88 12.31 62 93 11
Spines 26.4 26.8 5.66 1.03 21.46 15 38 30
Breadth/Length ratio 0.74 0.74 0.06 0.01 8.62 0.60 0.95 30
Aperture/Breadth ratio 0.53 0.52 0.05 0.009 9.05 0.4 0.6 30
Figure 54.

Light (A, B) and scanning electron (C-I) micrographs of Centropyxis giba. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two specimens to illustrate general shape and shell structure. (E) Dorsal view. (F) Lateral view. (G) Close up view of aperture to illustrate its circular shape and smooth surface around the aperture. (H) Close up view of a single spine to show its structure. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered mainly with diatom frustules.

Centropyxis laevigata Penard, 1890

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 151, Pl. V, fig. 42 à 44; 49 à 55.

Description: Shell colorless or yellowish, roughly circular (Fig. 55 A-E); main body spherical in lateral view and considerably compressed towards the aperture (Fig. 55 F); with rough surface and composed mainly of sand grains; only the region around the aperture is smooth and covered of organic cement (Fig. 55 C-I). Aperture large, circular or oval, invaginated, central or sub-central (Fig. 55 C-D, G).

Ecology: Frequent in aerophilic mosses and soils, very rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky et al. 2006).

Centropyxis laevigata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 80.9 80.5 6.69 1.05 8.28 71 99 41
Diameter of aperture 25.5 25.0 3.99 0.72 15.63 18 34 31
Depth 36.5 36.2 3.49 1.05 9.57 32 43 11
Aperture/Diameter ratio 0.31 0.31 0.04 0.007 12.95 0.2 0.5 31
Depth/Diameter ratio 0.47 0.45 0.06 0.02 13.03 0.4 0.6 11
Figure 55.

Light (A, B) and scanning electron (C-I) micrographs of Centropyxis laevigata. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Apertural view to show general shape and shell structure. (E) Dorsal view. (F) Lateral view. (G) Close up view of aperture showing its circular shape and smooth surface around the aperture. (H) Detail of smooth apertural surface. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered with sand grains.

Centropyxis orbicularis Deflandre, 1929

Original description: Deflandre 1929, Archiv für Protistenkunde, 67, p. 334, fig. 31 à 34.

Description: Shell yellow or brown, circular (Fig. 56 A-E); in lateral view almost uncompressed, spherical (Fig. 56 F); with smooth surface and composed mainly of flattish particles embedded in thick layer of organic cement, most abundant in the region around the aperture (Fig. 56 C-I). Aperture elliptical or oval, invaginated, sub-terminal (Fig. 56 C-D, G).

Ecology: Frequent in forest mosses and soils, very rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018).

Centropyxis orbicularis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 138.3 139.8 10.09 1.84 7.30 115 155 30
Diameter of aperture 71.9 71.0 7.57 1.38 10.51 55 83 30
Depth 89.0 90.6 5.47 1.65 6.14 74 94 11
Aperture/Diameter ratio 0.52 0.52 0.05 0.01 10.50 0.4 0.6 30
Depth/Diameter ratio 0.67 0.65 0.05 0.02 8.15 0.6 0.8 11
Figure 56.

Light (A, C) and scanning electron (B, D-I) micrographs of Centropyxis orbicularis. (A-B) View of several specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view showing general shape and shell structure. (E) Dorsal view. (F) Lateral view. (G) Close up view of aperture to illustrate its oval or elliptical shape and smooth surface around the aperture. (H) Detail of smooth apertural surface. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered mainly with flattish particles.

Centropyxis plagiostoma Bonnet and Thomas, 1955

Original description: Bonnet and Thomas 1955, Bulletin de la Société d’Histoire Naturelle de Toulouse, 90, p. 415, fig. 18, 19.

Description: Shell yellow or brown, circular (Fig. 57 A-F); in lateral view compressed and hemispherical (Fig. 57 G); with smooth apertural surface and rough dorsal surface; composed of small to medium pieces of quartz; region around the aperture covered mainly of flattish particles embedded in a thick layer of organic cement (Fig. 57 G, H). Aperture small, slightly invaginated, denticulated and surrounded by several large pieces of quartz, sub-terminal (Fig. 57 D-E, H).

Ecology: Frequent in forest mosses, litter and soils, very rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993).

Centropyxis plagiostoma. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 119.8 120.0 5.20 0.93 4.34 111 131 31
Diameter of aperture 29.2 29.2 3.99 0.83 13.68 22 35 23
Depth 63.4 63.3 3.71 1.12 5.85 58 69 11
Aperture/Diameter ratio 0.24 0.24 0.03 0.007 13.04 0.2 0.3 23
Depth/Diameter ratio 0.52 0.52 0.04 0.01 7.08 0.5 0.6 11
Figure 57.

Light (A, C) and scanning electron (B, D-I) micrographs of Centropyxis plagiostoma. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C-E) Apertural view of three specimens showing general shape and shell structure. (F) Dorsal view. (G) Lateral view. (H) Close up view of aperture to illustrate its denticulate shape. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered with pieces of quartz.

Centropyxis platystoma (Penard, 1890) Deflandre, 1929

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 143, Pl. IV, fig. 35 à 37; Last revision: Deflandre 1929, Archiv für Protistenkunde, 67, p. 338, fig. 43 à 57.

Synonyms: Difflugia platystoma Penard, 1890; Difflugia constricta p. p. Leidy, 1879, PL. XVIII, figs. 20-21; Difflugia constricta p. p. Penard, 1902, p. 299, figs. 8, 11, 12.

Description: Shell yellow or brown, elongate (Fig. 58 A-E); rounded in lateral view, sub-spherical in aboral region and considerably compressed in apertural region (Fig. 58 F); with smooth apertural surface and rough dorsal surface; composed of small to medium pieces of quartz occasionally mixed with diatom frustules; region around the aperture covered mainly of flattish particles embedded in a thick layer of organic cement (Fig. 58 E, H). Aperture large, invaginated, oval or circular, sub-terminal (Fig. 58 A-D, E, H).

Notes: C. platystoma is similar to C. elongata but differs from it by the rounded and subspherical aboral region, highly compressed visor and sharp border between the main body and the visor when viewed laterally.

Ecology: Frequent in Sphagnum and standing freshwater bodies, among submerged aquatic vegetation.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Centropyxis platystoma. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 115.0 114.6 6.90 1.09 6.00 101 132 40
Breadth 78.6 80.0 6.10 1.10 7.76 64 88 31
Diameter of aperture 42.6 42.4 3.80 0.69 8.93 35 51 30
Depth 72.7 73.5 3.07 0.93 4.23 68 77 11
Breadth/Length ratio 0.69 0.69 0.05 0.008 6.70 0.6 0.8 31
Aperture/Breadth ratio 0.37 0.37 0.03 0.005 7.90 0.3 0.5 30
Figure 58.

Light (A, B) and scanning electron (C-I) micrographs of Centropyxis platystoma. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D, E) Apertural view of two specimens showing general shape and shell structure. (F) Lateral view. (G) Dorsal view. (H) Close up view of aperture. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered with medium to large pieces of quartz.

Centropyxis spinosa (Cash, 1905) Deflandre, 1929

Original description: Cash and Hopkinson 1905, The British freshwater Rhizopoda and Heliozoa, Vol. I, p. 135, fig. 26, Pl. XVI, fig. 15; Last revision: Deflandre 1929, Archiv für Protistenkunde, 67, p. 353, fig. 108 à 111.

Synonyms: Centropyxis aculeata var. spinosa Cash, 1905.

Description: Shell yellowish-brownish, ovoid or circular, usually with four to ten lateral spines (Fig. 59 A-E).) ; in lateral view considerably compressed, discoid (Fig. 59 E, F); with comparatively smooth surface, composed of small sand grains, flattisg pieces of quartz and diatom frustules; region around the aperture smooth and covered mainly of organic cement (Fig. 59 B-F). Aperture large, circular or oval, invaginated and sub-terminal (Fig. 59 C, D, G).

Ecology: In Sphagnum and standing freshwater bodies, among submerged aquatic vegetation, rare.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Vitosha Mts. (Todorov 1993, Todorov and Golemansky 1995).

Centropyxis spinosa. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 123.0 124.2 7.13 1.22 5.80 107 136 34
Diameter of aperture 32.6 32.6 2.33 0.43 7.15 28 37 30
Depth 43.1 42.5 1.70 0.85 3.95 42 46 4
Spines 19.8 19.8 3.03 0.52 15.29 14 28 34
Aperture/Diameter ratio 0.26 0.26 0.02 0.004 8.12 0.2 0.3 30
Depth/Diameter ratio 0.38 0.38 0.009 0.005 2.43 0.37 0.39 4
Figure 59.

Light (A) and scanning electron (B-I) micrographs of Centropyxis spinosa. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view of two specimens to show general shape and shell structure. (E) Lateral view. (F) Latero-dorsal view. (G) Close up view of aperture showing its circular shape and smooth surface around the aperture. (H) Detail of posterior end of the shell to illustrate shape and structure of spines. (I) Detail of dorsal side of the shell showing its rough surface, covered mainly with flattish particles.

Bullinularia indica (Penard, 1907) Deflandre, 1953

Original description: Penard 1907, Journal of the Royal Microscopical Society, p. 274-277, Pl. XIV, Figs 1–4; Last revision: Deflandre 1953, Traité de Zoologie, v. I, fasc. II, p. 97, Pl. 1.

Synonyms: Bulinella indica Penard, 1907; Bullinula indica Penard, 1911.

Description: Shell dark brown, opaque, oval or circular in apertural and aboral views, hemispherical in lateral view (Fig. 60 A-F); composed mainly of small to medium flattish partticles, embedded in deep layer of organic cement on apertural side and large pieces of quartz on dorsal side (Fig. 60 D-F, I). Aperture narrow and elongated slit, with depressed inner lip and incurved outer lip with median extension, sub-terminal, invaginated, surrounded by numerous large pores (Fig. 60 D, G, H).

Ecology: Aerophilic, frequent in brown mosses, very rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Bankov et al. 2018).

Bullinularia indica. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 160.3 161.8 8.99 1.57 5.61 136 175 33
Breadth 183.1 183.6 10.61 1.62 5.80 156 206 34
Large axis of aperture 80.4 82.8 9.12 1.56 11.35 57 93 34
Depth 117.6 117.1 9.65 2.91 8.20 100 132 11
Breadth/Length ratio 1.14 1.14 0.05 0.009 4.35 1.1 1.3 33
Aperture/Breadth ratio 0.44 0.44 0.04 0.007 9.50 0.4 0.5 34
Figure 60.

Light (A, C) and scanning electron (B, D-I) micrographs of Bullinularia indica. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural views showing smooth apertural surface, characteristic aperture and large surrounding pores. (E) Lateral view. (F) Dorsal view. (G, H) Close up views of aperture to show its characteristic shape as an narrow, elongated slit. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered with large pieces of quartz.

Plagiopyxis callida Penard, 1910

Original description: Penard 1910, Revue Suisse de Zoologie, 18, p. 936, fig. 8-10.

Synonyms: Bullinula indica var. callida Jung, 1936.

Description: Shell yellow or brown, opaque, oval or circular in apertural and dorsal views, hemispherical in lateral view (Fig. 61 A-G); composed mainly of small to medium flattish particles, embedded in a thick layer of organic cement, smooth (Fig. 61 C- I). Aperture elliptical or oval, sub-terminal and invaginated; with deeply invaginated ventral side, partly covered by dorsal side (Fig. 61 A-D, H).

Ecology: Frequent in soils and brown mosses, accidentally in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rila Mts. (Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Plagiopyxis callida. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 97.5 97.8 4.04 0.64 4.15 87 107 40
Breadth 98.9 101.6 8.89 1.48 8.99 70 107 36
Large axis of aperture 52.3 53.7 6.14 1.25 11.75 40 61 24
Depth 70.2 69.6 6.16 1.78 8.78 57 78 12
Breadth/Length ratio 1.01 1.03 0.08 0.01 7.52 0.7 1.1 32
Aperture/Breadth ratio 0.54 0.55 0.04 0.009 7.75 0.4 0.6 24
Figure 61.

Light (A, B) and scanning electron (C-I) micrographs of Plagiopyxis callida. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Apertural view showing general shape. (E) Dorsal view (F, G) Lateral view. (H) Close up view of aperture showing its oval shape and smooth apertural surface. (I) Detail of dorsal side of the shell to illustrate its smooth surface, covered with flattish particles embedded in a thick layer of organic cement.

Plagiopyxis declivis Bonnet et Thomas, 1955

Original description: Bonnet and Thomas 1955, Bulletin de la Société d’Histoire Naturelle de Toulouse, 90, p. 420, fig. 10-11.

Description: Shell colorless or yellowish, circular or broadly oval in apertural and aboral views, hemispherical in lateral view (Fig. 62 A-G); smooth, with regular outline, composed mainly of small to medium flattish partticles, embedded in a thick layer of organic cement on apertural side and large pieces of quartz on dorsal side (Fig. 62 D- I). Aperture narrow and elongated slit, sub-terminal, invaginated; its ventral side is slightly invaginated and partly covered by dorsal side (Fig. 62 D, F-H).

Ecology: Frequent in soils and brown mosses, accidentally in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Plagiopyxis declivis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 75.1 76.0 4.29 0.73 5.71 65 82 35
Breadth 76.2 77.0 4.37 0.83 5.73 66 82 28
Large axis of aperture 27.6 27.0 3.70 0.87 13.4 23 34 24
Depth 37.7 38.5 2.67 0.85 7.10 33 41 10
Breadth/Length ratio 1.00 1.01 0.04 0.007 3.61 0.9 1.1 26
Aperture/Breadth ratio 0.37 0.37 0.04 0.009 10.04 0.3 0.4 17
Figure 62.

Light (A, C) and scanning electron (B, D-I) micrographs of Plagiopyxis declivis. (A-C) View of several specimens to illustrate variability in shape and size of the shell. (D) Apertural view showing general shape. (E) Dorsal view (F, G) Lateral views. (H) Close up view of aperture showing its shape as a narrow slit and smooth apertural surface. (I) Detail of dorsal side of the shell to illustrate its rough surface, covered with pieces of quartz.

Alabasta militaris (Penard, 1890) Duckert, Blandenier, Kosakyan and Singer, 2018

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 164, Pl. VII, fig. 16 à 22; Last revision: Duckert et al. 2018, European Journal of Protistology, 66, p. 162, fig. 1 A-D.

Synonyms: Nebela collaris Leidy, 1879 (pars); Nebela militaris Penard, 1890.

Description: Shell colourless, transparent, elongate-ovoid or pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture, forming short neck (Fig. 63 A-E); laterally compressed, with oval transverse section; with two lateral pores, not always well visible; composed of a mixture of oval, circular or rarely quadrangular, slightly overlapping shell-plates (Fig. 63 D-I). Aperture is an elongate slit, strongly curved, fan-shaped in broad view and deeply concave when viewed laterally, bordered by a thick collar of organic cement (Fig. 63 D-G). Cytoplasm granular, fills almost whole shell; cell attached to the posterior part of the shell wall with short epipodes; one ovular nucleus and numerous small nucleoli.

Notes: The species has been recorded as Nebela militaris.

Ecology: Aerophilic, in dry Sphagnum, as well as in brown mosses and forest litter.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Pateff 1924, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Alabasta militaris. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 70.1 68.5 5.45 0.98 7.77 62 87 31
Breadth 37.1 37.1 2.24 0.40 6.01 34 44 31
Large axis of aperture 17.9 18.5 1.89 0.34 10.56 12 20 31
Depth 23.5 23.0 2.96 0.69 12.59 21 32 18
Breadth/Length ratio 0.53 0.54 0.03 0.006 6.46 0.4 0.6 31
Aperture/Breadth ratio 0.48 0.49 0.05 0.009 10.47 0.3 0.5 31
Figure 63.

Light (A-C) and scanning electron (D-I) micrographs of Alabasta militaris. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C-E) Broad lateral view of three individuals to show the general shape. (F) Broad lateral view of apertural region showing strongly curved, fan-shaped aperture. (G) Narrow lateral view of aperture to illustrate its deep lateral notch and thick collar of organic cement. (H, I) Details of shell surface showing different shape and arrangement of shell-plates.

Gibbocarina galeata (Penard, 1890) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 161, Pl. VI, fig. 78 à 84.; Last revision: Kosakyan et al. 2016b, Cladistics, 32, p. 16.

Synonyms: Nebela galeata Penard, 1890.

Description: Shell colourless, transparent, pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture (Fig. 64 A-F); laterally compressed, with oval to ellipsoidal transverse section; has pronounced lateral margin or hollow tuberous keel, surrounding posterior end of the shell, and two lateral pores (Fig. 64 E-F, H); composed mainly of small, oval or circular, non-overlapping shell-plates, arranged haphazardly (Fig. 64 D-H). Aperture oval, slightly convex frontally and concave laterally, bordered by a thin collar of organic cement (Fig. 64 D-G, I). Cytoplasm granular, does not fills the whole shell, with numerous food vacuoles; cell attached to the posterior part of the shell wall with clearly visible long and thin epipodes; pseudopodia usually one or two, large, long, fast moving (Fig. 64 A, C).

Notes: The species has been recorded in both as nominal species and as synonym N. galeata.

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Gibbocarina galeata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 193.2 190.8 17.93 3.27 9.28 168 250 30
Breadth 115.7 114.5 18.02 3.29 15.58 83 158 30
Large axis of aperture 40.4 39.6 4.73 0.86 11.71 28 52 30
Depth 63.4 65.2 4.95 1.08 7.81 55 73 21
Breadth/Length ratio 0.60 0.59 0.07 0.01 11.06 0.5 0.7 30
Aperture/Breadth ratio 0.35 0.35 0.05 0.009 13.36 0.3 0.4 30
Figure 64.

Light (A, C) and scanning electron (B, D-I) micrographs of Gibbocarina galeata. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen to show granular cytoplasm, pseudopodia and epipodes. (D) Broad lateral view showing general shape. (E) Narrow lateral view to illustrate hollow tuberous keel. (F) Apertural view. (G) Lateral view of aperture. (H) Close up view of tuberous keel surrounding posterior end of the shell. (I) Close up view of aperture showing its oval outline and thin apertural collar.

Hyalosphenia papilio (Leidy, 1874) Leidy, 1875

Original description: Leidy 1874a, Proceedings of the Academy of Natural Sciences of Philadelphia, 26, p. 156; Last revision: Leidy 1875, Proceedings of the Academy of Natural Sciences of Philadelphia, 27, p. 415.

Synonyms: Difflugia (Catharia) papilio Leidy, 1874.

Description: Shell yellowish-brownish, transparent, smooth, ovoid, with sides tapering evenly and gradually from rounded aboral region towards to aperture; laterally compressed, elliptical in transverse section; with two or more pores on lateral margins (Fig. 65 A-G). Aperture terminal, broad, elliptical, slightly convex frontally and concave laterally, bordered by a thick collar of organic cement (Fig. 65 F-I). Cytoplasm granular, fills about two-thirds of the shell, always with numerous symbiotic zoochlorellae; cell attached to the posterior part of the shell wall with numerous epipodes; one large ovular nucleus and many small nucleoli; encysted specimens frequently seen, cysts round or ovale, with thick organic wall, occupying central region of the shell (Fig. 65 A-C, E). Pseudopodia usually two to three, rarely numerous, long, digitiform, fast moving (Fig. 65 B-D).

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mt. (Bankov et al. 2018); Rhodopes Mt. (Golemansky 1968, Golemansky et al. 2006); Rila Mt. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mt. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Hyalosphenia papilio. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 116.4 116.7 5.72 1.03 4.92 106 129 31
Breadth 68.8 69.1 6.07 1.03 8.82 54 82 31
Large axis of aperture 33.0 33.1 3.39 0.61 10.27 27 40 31
Depth 38.9 38.9 3.43 0.66 8.82 33 44 27
Breadth/Length ratio 0.59 0.59 0.04 0.007 7.00 0.5 0.7 31
Aperture/Breadth ratio 0.48 0.48 0.04 0.007 7.64 0.4 0.6 31
Figure 65.

Light (A-E) and scanning electron (F-I) micrographs of Hyalosphenia papilio. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) View of live specimen to illustrate the cytoplasm with symbiotic zoochlorellae, pseudopodia and epipodes. (E) View of encysted specimen showing round cyst. (F) Broad lateral view. (G) Narrow lateral view. (H) Broad lateral view of apertural region. (I) Close up view of aperture to illustrate its elliptical shape and bordering thick collar of organic cement.

Longinebela ampulla Todorov, Bankov and Ganeva, 2018

Original description: Todorov et al. 2018, Acta zoologica bulgarica, 70 (3), p. 287, Fig. 1 A-D, Fig. 3 A-C.

Description: Shell colourless, elongated-cylindrical, with distinct short neck and rounded aboral region (Fig. 66 A-E); laterally flattened only in the region of neck; all remaining part of the shell almost uncompressed laterally, without lateral margins and lateral pores (Fig. 66 E); composed mainly of small, oval, rarely circular shell-plates, arranged regularly without overlapping and embedded in thick layer of organic cement; their outer part appears to be covered with layer of cement, thus edges are not clearly defined (Fig. 66 G, I). Aperture oval, truncate but not convex, bordered by a thin collar of organic cement (Fig. 66 H).

Notes: L. ampulla can clearly be discriminated from L. penardiana by its elongated cylindrical shell, almost uncompressed laterally and flattened in the region of the neck only; absence of lateral margins and lateral pores; view of the aperture which is not convex but rather truncate and not concave in lateral view; structure of the shell which is composed mainly of small oval, rarely circular shell plates, embedded in a thick layer of organic cement.

Ecology: L. ampulla is found in wet moss Sphagnum flexuosum, growing on a small mire in a mixed deciduous forest of beech (Fagus sylvatica L.) and birch (Betula pendula L.); rare species with a low density.

Geographical distribution: Recently described from Bulgaria; unknown distribution.

Distribution in Sphagnum mosses in Bulgaria: Stara Planina Mts. (Todorov et al. 2018).

Longinebela ampulla. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 125.8 125.9 3.53 0.61 2.81 117 131 33
Breadth 45.9 45.6 1.92 0.33 4.18 43 51 33
Depth 43.2 43.2 0.82 0.16 1.90 42 45 27
Large axis of aperture 23.5 23.7 1.37 0.24 5.83 21 27 33
Small axis of aperture 12.4 11.9 1.32 0.25 10.6 10 16 27
Length of neck 6.6 6.5 1.05 0.18 15.9 5 9 27
Breadth/Length ratio 0.36 0.36 0.01 0.002 2.78 0.35 0.39 33
Depth/Breadth ratio 0.95 0.95 0.02 0.003 2.10 0.92 0.99 27
Figure 66.

Light (A-C) and scanning electron (D-I) micrographs of Longinebela ampulla. (A-E) Broad lateral views to illustrate characteristic form of the ampoule. (F) Narrow lateral view showing absence of lateral compression, lateral margins and pores. (G) Broad lateral view of the apertural region to show distinct short neck and shell strucrure. (H) Apertural view showing aperture outline and thin apertural collar. (I) Detail of shell surface showing shell plates and abundant organic cement.

Longinebela golemanskyi (Todorov, 2010) Kosakyan, Lahr, Mulot, Meisterfeld,Mitchell and Lara, 2016

Original description: Todorov 2010, Acta Protozoologica, 49, p. 38, Figs 1–12; Last revision: Kosakyan et al. 2016b, Cladistics, 32, p. 16.

Synonyms: Nebela golemanskyi Todorov, 2010.

Description: Shell colourless, transparent, pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture, forming short neck (Fig. 67 A, C-E); almost uncompressed laterally, with circular or broadly oval transverse section; without lateral margins and lateral pores (Fig. 67 C-F); with thick wall, composed of voluminous, globular or rarely elongated, rounded siliceous shell-plates (Fig. 67 C-I); large parts of organic cement, in a form of small beads usually well visible between plates (Fig. 67 H-I). Aperture roughly circular to oval, truncate, bordered by a thin collar of organic cement (Fig. 67 E-H).

Notes: Longinebela golemanskyi differs from L. speciosa by its uncompressed shell, characteristic voluminous shell-plates, absence of lateral margins and roughly circular, non convex but truncate aperture. The species has been recorded in both as nominal species and as N. golemanskyi.

Ecology: In Sphagnum, very rare.

Geographical distribution: Recently described from Bulgaria; unknown distribution.

Distribution in Sphagnum mosses in Bulgaria: Vitosha Mts. (Todorov 2010, Bankov et al. 2018).

Longinebela golemanskyi. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 212.8 212.5 9.47 1.58 4.45 198 239 36
Breadth 118.0 117.8 5.77 0.96 4.89 105 132 36
Large axis of aperture 39.2 39.0 2.31 0.38 5.90 36 45 36
Depth 94.8 94.5 3.28 0.67 3.46 89 100 24
Breadth /Length ratio 0.56 0.56 0.03 0.005 5.41 0.5 0.6 36
Aperture/Breadth ratio 0.33 0.33 0.02 0.003 6.22 0.3 0.4 36
Figure 67.

Light (A, B) and scanning electron (C-I) micrographs of Longinebela golemanskyi. (A-D) Broad lateral view to illustrate general shape and characteristic voluminous siliceous shell-plates. (E) Latero-apertural view. (F) Apertural view. (G) Close up view of aperture showing aperture outline and collar of organic cement. (H) Lateral view of apertural region. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Longinebela penardiana (Deflandre, 1936) Kosakyan, Lahr, Mulot, Meisterfeld,Mitchell and Lara, 2016

Original description: Deflandre 1936, Annales de Protistologie, 5, p. 257, fig. 87 à 89, PL. XIX, fig. 1 à 9, Pl. XX, fig. 1, 2, 4, 5, 7; Last revision: Kosakyan et al. 2016b, Cladistics, 32, p. 16.

Synonyms: Nebela penardiana Deflandre, 1936.

Description: Shell colourless or brownish, transparent, elongate-pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture (Fig. 68 A-D); laterally compressed, with oval transverse section; with small lateral margins and two lateral pores usually well visible on the first third of lateral margins (Fig. 68 C, D; composed of small, oval, circular or rarely quadrangular, overlapping shell-plates, arranged haphazardly (Fig. 68 D-G). Aperture oval, slightly convex frontally and concave laterally, bordered by a collar of organic cement (Fig. 68 E, F, H, I). Cytoplasm granular, fills about two-thirds of the shell; cell attached to the posterior part of the shell wall with clearly visible epipodes. Pseudopodia usually one or two, large, long, fast moving (Fig. 68 A, C).

Notes: The species has been recorded in both as nominal species and as N. penardiana.

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Kosakyan et al. 2012, Bankov et al. 2018).

Longinebela penardiana. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 156.3 151.1 12.92 2.10 8.27 138 189 38
Breadth 71.7 69.6 8.59 1.39 11.97 55 87 38
Large axis of aperture 28.7 28.5 2.52 0.41 8.80 22 34 38
Depth 53.4 51.1 6.58 1.65 12.32 46 71 16
Breadth/Length ratio 0.46 0.46 0.04 0.006 8.10 0.4 0.5 38
Aperture/Breadth ratio 0.40 0.40 0.05 0.007 11.17 0.3 0.5 38
Figure 68.

Light (A, C) and scanning electron (B, D-I) micrographs of Longinebela penardiana. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing granular cytoplasm, pseudopodia and epipodes. (D) Broad lateral view to show general shape and arrangement of shell-plates. (E) Lateral view. (F) Apertural view. (G) Detail of shell surface showing shape and arrangement of shell-plates. (H) Broad lateral view of apertural region. (I) Close up view of aperture to show aperture outline and collar of organic cement.

Longinebela speciosa (Deflandre, 1936) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016

Original description: Deflandre 1936, Annales de Protistologie, 5, p. 259, Pl. XX, fig. 3, 6, 8; Last revision: Kosakyan et al. 2016b, Cladistics, 32, p. 16.

Synonyms: Nebela speciosa Deflandre, 1936.

Description: Shell colourless or brownish, transparent, elongated-pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture (Fig. 69 A-D); slightly compressed laterally, with oval transverse section; with small lateral margins which do not extend around the aboral region, two lateral pores on the first one third of lateral margins (Fig. 69 E, F); composed of small, oval, circular or rarely quadrangular, overlapping shell-plates, arranged haphazardly (Fig. 69 D-H). Aperture oval, slightly convex frontally and concave laterally, bordered by a collar of organic cement (Fig. 69 F-I). Cytoplasm fulfilled with many dark-brown granules, fills about two-thirds of the shell; cell attached to the posterior part of the shell wall with numerous, clearly visible epipodes; pseudopodia usually three to five, large, not very long, fast moving (Fig. 69 A, C).

Notes: The species has been recorded in both as nominal species and as N. speciosa.

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Kosakyan et al. 2012, Bankov et al. 2018).

Longinebela speciosa. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 259.9 261.5 10.80 1.94 4.15 241 284 31
Breadth 116.1 116.6 7.95 1.43 6.85 99 138 31
Large axis of aperture 48.2 48.4 3.48 0.62 7.21 39 54 31
Depth 90.1 88.5 6.29 1.26 6.96 81 102 25
Breadth/Length ratio 0.45 0.44 0.03 0.006 7.73 0.4 0.5 31
Aperture/Breadth ratio 0.42 0.42 0.03 0.006 7.77 0.3 0.5 31
Figure 69.

Light (A, C) and scanning electron (B, D-I) micrographs of Longinebela speciosa. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing granular cytoplasm, pseudopodia and epipodes. (D) Broad lateral view showing general shape and arrangement of shell-plates. (E) Lateral view. (F) Apertural view. (G) Narrow lateral view of apertural region to show laterally concave aperture. (H) Broad lateral view of apertural region. (I) Close up view of aperture showing aperture outline and collar of organic cement.

Longinebela tubulosa (Penard, 1890) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 159; Last revision: Kosakyan et al. 2016b, Cladistics, 32, p. 16.

Synonyms: Nebela tubulosa Penard, 1890.

Description: Shell yellow or brown, transparent, pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture, forming short neck (Fig. 70 A-E); laterally compressed, oval transverse section; with lateral margins beginning at the base of the neck and extending all around; two lateral pores usually present on the first one third of lateral margins (Fig. 70 F); composed mainly of small, oval or circular, overlapping shell-plates, arranged haphazardly and embedded in thick layer of organic cement (Fig. 70 D, E, G, I). Aperture oval, slightly convex, bordered by a thin collar of organic cement (Fig. 70 G, H). Cytoplasm granular, fills about two-thirds of the shell; cell attached to the posterior part of the shell wall with clearly visible epipodes; one large ovular nucleus and numerous nucleoli; pseudopodia usually one or two, large, long, fast moving (Fig. 70 A-C).

Notes: The species has been recorded in both as nominal species and as synonym N. tubulosa (Rila Mts., Stara Planina Mts., Vitosha Mts.).

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Todorov 1993, Todorov and Golemansky 1995, Kosakyan et al. 2012, Bankov et al. 2018).

Longinebela tubulosa. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 226.6 224.2 25.37 4.49 11.20 189 282 32
Breadth 125.3 117.3 21.17 3.74 16.90 92 168 32
Large axis of aperture 53.8 52.4 8.17 1.44 15.18 42 68 32
Depth 68.3 65.6 8.98 2.40 13.14 57 85 14
Breadth/Length ratio 0.55 0.55 0.05 0.008 8.67 0.4 0.7 32
Aperture/Breadth ratio 0.43 0.43 0.03 0.006 8.04 0.4 0.5 32
Figure 70.

Light (A-C) and scanning electron (D-I) micrographs of Longinebela tubulosa. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing granular cytoplasm, pseudopodia and epipodes. (D, E) Broad lateral view to show general shape and arrangement of shell-plates. (F) Apertural view. (G) Broad lateral view of apertural region. (H) Close up view of aperture to show aperture outline and thin apertural collar. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Nebela aliciae Mitchell et Lara, 2013

Original description: Kosakyan et al. 2013, European Journal of Protistology, 49 (2), p. 234, Figs 6A, B, 7A.

Description: Shell colorless or yellowish, transparent, ovoid or pyriform, with broadly rounded aboral region and well-expressed lateral keel of about 5-6 μm wide (Fig. 71 A-D, G, H); laterally compressed, with oval transverse section, two well visible lateral pores (Fig. 71 A-C); composed of small, oval or circular, slightly overlapping shell-plates, arranged haphazardly and embedded in thick layer of organic cement (Fig. 71 A- I). Aperture oval, slightly convex or truncate, bordered by a thin collar of organic cement (Fig. 71 A, B, E, F).

Ecology: In Sphagnum, rare.

Geographical distribution: Recently described from Costa Rica, still unknown.

Distribution in Sphagnum mosses in Bulgaria: Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Nebela aliciae. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 134.3 136.1 16.27 5.75 12.12 109 155 8
Breadth 111.3 112.8 12.70 4.80 11.40 88 127 7
Large axis of aperture 32.4 33.0 3.22 1.22 9.93 27 37 7
Depth 52.6 52.6 3.39 2.40 6.45 50 55 2
Breadth/Length ratio 0.82 0.82 0.05 0.02 5.60 0.8 0.9 7
Aperture/Breadth ratio 0.29 0.29 0.02 0.008 7.55 0.25 0.32 7
Figure 71.

Scanning electron micrographs of Nebela aliciae. (A, B) Broad lateral views of two specimens to illustrate general shape. (C) Narrow lateral view to show lateral keel. (D) Close up view of lateral keel showing its structure. (E, F) Broad lateral view of apertural region to illustrate aperture outline and collar of organic cement. (G, H) Close up view of lateral keel. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Nebela collaris (Ehrenberg, 1848) Leidy, 1879

Original description: Ehrenberg 1848a, Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königliche Preussischen Akademie der Wissenschaften zu Berlin, 13, p. 218; Last revision: Leidy 1879, Report of the United States Geological Survey of the Territories, 12, p. 145, Pl. XXII, figs. 1-10, 13-15, 17-20, Pl. XXVI, fig. 11.

Synonyms: Difflugia collaris Ehrenberg, 1848; Difflugia cancellata Ehrenberg, 1848; Difflugia reticulata Ehrenberg, 1848; Difflugia carpio Ehrenberg, 1854; Difflugia laxa Ehrenberg, 1871; Difflugia cellulifera Ehrenberg, 1874; Nebela numata Leidy, 1874; Nebela bohemica Taranek, 1882; Nebela sphagnophila (Steinecke) Van Oye, 1933; Nebela tincta var. major Deflandre, 1936; Nebela tincta f. stenostoma Jung, 1936.

Description: Shell colourless, transparent, ovoid, with sides tapering evenly and gradually from rounded aboral region towards to aperture, sometimes forming short neck (Fig. 72 A-E); laterally compressed, oval transverse section; with two lateral pores usually well visible (Fig. 72 F); composed of small, oval, circular or rarely quadrangular shell-plates, arranged regularly, do not overlapping (Fig. 72 E-F, G, I). Aperture oval, slightly convex or truncate, bordered by a thin collar of organic cement (Fig. 72 E-H). Cytoplasm granular, fills almost whole shell; cell attached to the posterior part of the shell wall with clearly visible epipodes; one large ovular nucleus and numerous small nucleoli; pseudopodia usually three to five, large, long, fast moving (Fig. 72 A, C, D).

Ecology: Common in Sphagnum, as well as in brown mosses and forest litter.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Kosakyan et al. 2012; Bankov et al. 2018).

Nebela collaris. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 118,3 118,0 4,99 0,91 4,22 110 130 30
Breadth 76,0 75,1 5,15 0,94 6,78 67 85 30
Large axis of aperture 26,4 26,7 2,56 0,47 9,68 20 35 30
Depth 42,5 42,7 3,88 0,89 9,14 36 50 19
Breadth/Length ratio 0,64 0,64 0,04 0,007 6,48 0,5 0,7 30
Aperture/Breadth ratio 0,35 0,35 0,03 0,005 8,50 0.3 0,4 30
Figure 72.

Light (A, C, D) and scanning electron (B, E-I) micrographs of Nebela collaris. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) View of live specimens showing granular cytoplasm, pseudopodia and epipodes. (E) Broad lateral view. (F) Apertural view. (G) Broad lateral view of apertural region. (H) Close up view of aperture showing aperture outline and collar of organic cement. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Nebela flabellulum Leidy, 1874

Original description: Leidy 1874b, Proceedings of the Academy of Natural Sciences of Philadelphia, 26, p. 157.

Synonyms: Difflugia (Nebela) flabellulum Leidy, 1874.

Description: Shell colourless, transparent, circular or ellipsoidal, wider than long, with broadly rounded aboral region and well-defined short neck (Fig. 73 A-E); laterally compressed, oval transverse section, with two lateral pores usually well visible (Fig. 73 F); composed of small, oval or circular, overlapping shell-plates, arranged haphazardly and embedded in thick layer of organic cement (Fig. 73 C-F, H, I). Aperture oval, slightly convex or truncate, bordered by a thin collar of organic cement (Fig. 73 C-H). Cytoplasm granular, with numerous food vacuoles, fills about two-thirds of the shell; cell attached to the posterior part of the shell wall with numerous, clearly visible epipodes; pseudopodia usually three to five, large, long and fast moving.

Notes: Nebela flabellulum differs from N. tincta and N. collaris mainly by being wider than long.

Ecology: In Sphagnum, very rare in Bulgaria.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Stara Planina Mts. (Bankov et al. 2018).

Nebela flabellulum. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 88.5 87 4.84 1.34 5.47 82 99 13
Breadth 93.1 92.2 7.04 1.82 7.56 84 105 15
Large axis of aperture 19.6 19.8 1.92 0.50 9.81 17 23 15
Depth 43 43 43 43 1
Breadth/Length ratio 1.05 1.06 0.05 0.01 4.52 0.98 1.11 13
Aperture/Breadth ratio 0.21 0.21 0.02 0.005 9.23 0.2 0.3 15
Figure 73.

Light (A) and scanning electron (B-I) micrographs of Nebela flabellulum. (A-E) View of different specimens to illustrate variability in shape and size of the shell. (F) Apertural view. (G) Close up view of aperture showing aperture outline and collar of organic cement. (H) Broad lateral view of apertural region. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Nebela tincta (Leidy, 1879) Awerintzew, 1906

Original description: Leidy 1879, Report of the United States Geological Survey of the Territories, 12, p. 138, Pl. XX, figs. 11-17; Last revision: Awerintzew 1906, Trudui Imperatorskago Sankt Peterburgskago Obshchestva Estestvoispitateleì, 36 (2), p. 249.

Synonyms: Hyalosphenia tincta Leidy, 1879; Nebela bursella Vejdovsky, 1882; Nebela minor Penard, 1902; Nebela parvula Cash, 1909.

Description: Shell yellowish, transparent, ovoid, with broadly rounded aboral region and well-defined short neck (Fig. 74 A-D); laterally compressed, with oval transverse section; two well visible lateral pores (Fig. 74 E, F); composed of small, oval or circular, overlapping shell-plates, arranged haphazardly and embedded in thick layer of organic cement (Fig. 74 D-F, H, I). Aperture oval, slightly convex or truncate, bordered by a thin collar of organic cement (Fig. 74 C-H). Cytoplasm granular, with numerous food vacuoles, fills about two-thirds of the shell; one large ovular nucleus and numerous small nucleoli; pseudopodia usually three to six, not very long, fast moving.

Notes: The species has been recorded in both as nominal species and as synonyms N. bursella, N. minor and N. parvula.

Ecology: In Sphagnum, as well as in brown mosses and forest litter.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Golemansky and Todorov 1993, Todorov and Golemansky 2000, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Nebela tincta. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 80.6 80.6 5.18 0.95 6.43 71 90 30
Breadth 58.5 58.6 3.49 0.64 5.96 52 67 30
Large axis of aperture 17.5 17.4 1.71 0.31 9.77 15 21 30
Depth 34.5 34.5 2.03 0.64 5.89 30 37 10
Breadth/Length ratio 0.73 0.72 0.03 0.005 4.13 0.7 0.8 30
Aperture/Breadth ratio 0.30 0.29 0.02 0,005 8.34 0.3 0,4 30
Figure 74.

Light (A, B) and scanning electron (C-I) micrographs of Nebela tincta. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Broad lateral view to show general shape (E) Narrow lateral view. (F) Apertural view showing lateral pores. (G) Close up view of aperture to illustrate aperture outline and collar of organic cement. (H) Broad lateral view of apertural region. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Padaungiella lageniformis (Penard, 1890) Lara et Todorov, 2012

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 158, Pl. VI, fig. 50 à 61; Last revision: Kosakyan et al. 2012, Protist, 163, p. 430, Fig. 6 A.

Synonyms: Nebela lageniformis Penard, 1890.

Description: Shell colourless, transparent, flask-shaped, with rounded aboral region and distinct long neck (Fig. 75 A-E); slightly compressed laterally, with oval transverse section and without lateral borders and lateral pores (Fig. 75 F); composed of small, oval, circular or quadrangular, overlapping shell-plates, arranged haphazardly (Fig. 75 D-F, I). Aperture oval, slightly convex frontally and concave laterally, bordered by a collar of organic cement (Fig. 75 D-H). Cytoplasm fulfilled with many granules and food vacuoles, fills almost whole shell; one large ovular nucleus and numerous small nucleoli; pseudopodia usually three to five, large, not very long, fast moving (Fig. 75 A, C).

Notes: The species has been recorded in both as nominal species and as N. lageniformis.

Ecology: Common in Sphagnum, rarely in forest litter and soils.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Kosakyan et al. 2012).

Padaungiella lageniformis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 118.9 120.3 8.42 1.51 7.08 101 136 31
Breadth 57.8 58.0 3.74 0.67 6.47 46 66 31
Large axis of aperture 24.4 24.4 2.08 0.37 8.52 21 29 31
Depth 39.2 38.6 3.26 0.90 8.32 34 46 13
Breadth/Length ratio 0.49 0.49 0.04 0.007 7.54 0.4 0.6 31
Aperture/Breadth ratio 0.42 0.42 0.03 0.005 7.26 0.4 0.5 31
Figure 75.

Light (A, C) and scanning electron (B, D-I) micrographs of Padaungiella lageniformis. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing granular cytoplasm fulfilled with many food vacuoles and large nucleus. (D, E) Broad lateral view of two individuals showing general shape and arrangement of shell-plates. (F) Narrow lateral view. (F) Apertural view. (H) Broad lateral view of apertural region showing a thin collar of organic cement. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Padaungiella nebeloides (Gauthier-Lièvre and Thomas, 1958) Lara et Todorov, 2012

Original description: Gauthier-Lièvre et Thomas 1958, Archiv für Protistenkunde, 103, p. 341, Fig. 54; Last revision: Kosakyan et al. 2012, Protist, 163, p. 430, Fig. 6 G, H.

Synonyms: Difflugia nebeloides Gauthier-Lièvre and Thomas, 1958; Nebela nebeloides (Gauthier-Lièvre and Thomas, 1958) Todorov, Golemansky and Meisterfeld, 2010.

Description: Shell yellowish-brawnish, elongated-pyriform, rounded aborally, tapering evenly towards to aperture and forming distinct neck in the anterior one third of the shell (Fig. 76 A-D); uncompressed, with circular transverse section (Fig. 76 E); composed of various in size oval, circular and quadrangular, overlapping shell-plates, arranged haphazardly, sometimes mixed with small to medium flattish pieces of quartz (Fig. 76 C, D, F, H). Organic cement is frequently seen between shell-plates; small single pores of about 200-250 nm in diameter usually well visible in the cement (Fig. 76 F, I). Aperture with irregular outline, bordered by a thick collar of organic cement, with an uneven and undulating rim (Fig. 76 C-G).

Notes: The species has been recorded in both as nominal species and as N. nebeloides. It should be noted that Mazei and Waren (2014) erroneously synonymized D. nebeloides with D. linearis (Penard, 1890) Gautier-Lièvre et Thomas, 1958, because they have not taken into account the fact that this species has recently been transferred from the genus Difflugia into the genus Nebela (Todorov et al. 2010) and subsequently in the newly described genus Padaungiella (Kosakyan et al., 2012).

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Todorov et al. 2010, Bankov et al. 2018).

Padaungiella nebeloides. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 124.9 124.4 6.47 0.59 5.18 113 148 125
Breadth 48.6 48.0 3.17 0.28 6.53 43 59 125
Diameter of aperture 20.0 19.0 2.84 0.25 14.24 17 38 125
Breadth/Length ratio 0.39 0.39 0.02 0.002 5.40 0.3 0.5 125
Aperture/Breadth ratio 0.41 0.40 0.04 0.004 10.73 0.3 0.6 125
Figure 76.

Light (A, B) and scanning electron (C-I) micrographs of Padaungiella nebeloides. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Broad lateral view of two individuals showing general shape. (E) Apertural view. (F) Broad lateral view of apertural region showing a thick collar of organic cement and uneven, undulating rim. (G) Close up view of aperture to show its irregular outline. (H) Detail of shell surface showing shape and arrangement of shell-plates. (I) Detail of shell surface to illustrate small pores in the organic cement.

Padaungiella tubulata (Brown, 1910) Lara et Todorov, 2012

Original description: Brown 1910, Journal of the Linnean Society of London, Zoology, 30, p. 365, Pl. 50, figs. 9-10; Last revision: Kosakyan et al. 2012, Protist, 163, p. 430.

Synonyms: Nebela militaris var. tubulata Brown, 1910; Nebela tubulata Brown, 1911.

Description: Shell colourless, transparent, flask-shaped, with rounded or ovoid aboral region and distinct long, thin neck with parallel sides (Fig. 77 A-E); slightly compressed laterally, with oval transverse section, without lateral borders and lateral pores (Fig. 77 F); composed of small, oval or circular, slightly overlapping shell-plates, arranged haphazardly (Fig. 77 D, E, G-I). Aperture oval, convex frontally and concave laterally, bordered by a thick collar of organic cement (Fig. 77 B, D-F). Cytoplasm granular, fills almost whole shell. Pseudopodia usually a few, large, not very long, fast moving.

Notes: The species has been recorded in both as nominal species and as N. tubulata.

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Padaungiella tubulata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 82.9 83.0 4.28 0.77 5.17 74 90 31
Breadth 35.6 36.0 2.60 0.47 7.28 31 40 31
Large axis of aperture 15.8 16.0 1.59 0.29 10.11 11 19 31
Depth 25.8 26.0 1.70 0.40 6.58 23 29 18
Breadth/Length ratio 0.43 0.43 0.03 0.005 6.36 0.4 0.5 31
Aperture/Breadth ratio 0.44 0.44 0.05 0.009 10.87 0.3 0.6 31
Figure 77.

Light (A, B) and scanning electron (C-I) micrographs of Padaungiella tubulata. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D, E) Broad lateral view of two individuals showing general shape and arrangement of shell-plates. (F) Lateral view. (G) Latero-apertural view. (H) Broad lateral view of apertural region showing a thin collar of organic cement and convex border of the aperture. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Padaungiella wailesi (Deflandre, 1936) Lara et Todorov, 2012

Original description: Deflandre 1936, Annales de Protistologie, 5, p. 265, Fig. 100, 103 (p. 262), Pl. XXII, fig. 6 à 9, PL. XXIII, fig. 1 à 4; Last revision: Kosakyan et al. 2012, Protist, 163, p. 430, Fig. 6 E, F.

Synonyms: Nebela wailesi Deflandre, 1936.

Description: Shell colourless, transparent, flask-shaped, with rounded aboral region, elliptic body and distinct neck of about one third of the total length (Fig. 78 A-E); slightly compressed laterally, with oval transverse section, without lateral borders and lateral pores (Fig. 78 F); composed of different in shape and size oval, circular or rarely quadrangular, overlapping shell-plates, arranged haphazardly (Fig. 78 C-E, I). Aperture oval, slightly convex frontally and concave laterally, bordered by a thick collar of organic cement (Fig. 78 D-H). Cytoplasm granular, usually with many food vacuoles, does not fills the whole shell. Pseudopodia usually one or two, large, not very long, fast moving. (Fig. 78 A, B).

Notes: The species has been recorded by the synonymous name N. wailesi. Padaungiella wailesi is very similar to P. lageniformis but differs from it by the smaller size, shorter neck, not so pronounced boundary betweem elliptic body and neck, as well as by its ecological preferences.

Ecology: Common in litter, mosses and soils in deciduous forests, rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky et al. 2006).

Padaungiella wailesi. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 107,6 106,5 5,25 0,91 4,88 95 117 33
Breadth 55,4 55,2 1,78 0,31 3,21 52 58 33
Large axis of aperture 21,2 21,4 1,22 0,21 5,75 19 24 33
Depth 30,7 30,7 1,21 0,21 3,94 28 33 33
Breadth/Length ratio 0,52 0,52 0,02 0,003 3,85 0,49 0,55 33
Aperture/Breadth ratio 0,38 0,38 0,02 0,004 5,26 0,33 0,42 33
Figure 78.

Light (A, B) and scanning electron (C-I) micrographs of Padaungiella wailesi. (A) View of several specimens to illustrate variability in shape and size of the shell. (B) View of live specimen showing granular cytoplasm and pseudopodia. (C-E) Broad lateral view of three specimens showing different shape and size of shell-plates. (F) Narrow lateral view. (G) Apertural view. (H) Broad lateral view of apertural region showing a thick collar of organic cement. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Planocarina carinata (Archer, 1867) Kosakyan, Lahr, Mulot, Meisterfeld, Mitchelland Lara, 2016

Original description: Archer 1867, Quarterly Journal of Microscopical Science, 7, p. 178; Last revision: Kosakyan et al. 2016b, Cladistics, 32, p. 17.

Synonyms: Nebela carinata (Archer, 1867) Leidy, 1879.

Description: Shell colourless, transparent, pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture (Fig. 79 A-E); laterally compressed, oval to ellipsoidal transverse section; with pronounced flattened lateral margin, surrounding almost entirely the shell, two lateral pores (Fig. 79 F-G); composed mainly of small, oval or circular, mainly flattish, slightly overlapping shell-plates, arranged haphazardly and embedded in thick layer of organic cement (Fig. 79 E-I). Aperture oval, slightly convex or truncate, bordered by thin collar of organic cement (Fig. 79 E-H).

Notes: Planocarina carinata differs from P. marginata and G. galeata by the pronounced, broad and strongly flattened lateral margin. The species has been recorded in both as nominal species and as synonym N. carinata.

Ecology: In Sphagnum, very rare in Bulgaria.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rila Mts. (Golemansky and Todorov 1993); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995).

Planocarina carinata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 184.2 185.6 9.48 1.40 5.15 156 204 46
Breadth 119.3 119.5 8.02 1.18 6.72 102 133 46
Large axis of aperture 40.4 40.6 2.42 0.36 5.99 36 47 46
Depth 64.2 64.0 3.77 1.68 5.87 60 70 5
Breadth/Length ratio 0.65 0.65 0.03 0.005 4.61 0.6 0.8 46
Aperture/Breadth ratio 0.34 0.33 0.03 0.004 8.82 0.3 0.4 46
Figure 79.

Light (A-D) and scanning electron (E-I) micrographs of Planocarina carinata. (A) View of several specimens to illustrate variability in shape and size of the shell. (B-E) Broad lateral view of four specimens showing general shape and distinct flattened lateral margin. (F) Latero-apertural view to illustrate flattened lateral margin and lateral pore. (G) Apertural view. (H) Close up view of aperture showing its oval outline and thin apertural collar. (I) Detail of shell surface to illustrate shape and arrangement of shell-plates in thick layer of organic cement.

Quadrulella longicollis (Taranek, 1882)

Original description: Taranek 1882, Abhandlungen der Königlich Böhmischen Gesellschaft der Wissenschaften, 11, p. 48, Taf. IV, fig. 19; Last revision: Kosakyan et al. 2012, p. 429, Fig. 5D.

Synonyms: Quadrulella symmetrica var. longicollis Taranek, 1882.

Description: Shell colourless, transparent, elongate-pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture, forming long neck; laterally compressed, with oval transverse section (Fig. 80 A-E); composed of quadrangular shell-plates with different size, smaller near the aperture, usually arranged in rows (Fig. 80 C-F, I). Aperture terminal, oval, slightly convex frontally and concave laterally, bordered by a thin collar of organic cement (Fig. 80 C, D, F-H). Cytoplasm granular, fills about two-thirds of the shell, with numerous food vacuoles; one large ovular nucleus with a few small nucleoli. Pseudopodia usually one or two, long, digitiform, fast moving.

Notes: The species has been recorded in both as nominal species and as Quadrulella symmetrica var. longicollis. Quadrulella longicollis differs from Q. symmetrica by its larger size and by the elongated shell with pronounced long neck (B/L ratio 0.3-0.5 versus 0.5-0.7).

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Kosakyan et al. 2012, Bankov et al. 2018).

Quadrulella longicollis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 120.0 119.6 10.63 1.94 8.86 103 156 30
Breadth 53.5 54.1 4.95 0.90 9.25 42 62 30
Aperture width 23.5 23.7 2.84 0.52 12.08 18 30 30
Depth 38.8 38.1 3.99 1.07 10.28 32 46 14
Breadth/Length ratio 0.45 0.46 0.04 0.008 9.63 0.3 0.5 30
Aperture/Breadth ratio 0.44 0.44 0.05 0.01 12.36 0.4 0.6 30
Figure 80.

Light (A) and scanning electron (B-I) micrographs of Quadrulella longicollis. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Broad lateral view of two individuals to show the general shape. (E) Narrow lateral view. (F) Apertural view. (G) Close up view of aperture to illustrate its elliptical shape and bordering thin collar of organic cement (H) Lateral view of aperture. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Quadrulella symmetrica (Wallich, 1863) Cockerell, 1909

Original description: Wallich 1863, Annals and Magazine of Natural History, ser. 3, v. 12, no 72, p. 458, Pl. 8, fig. 16; Last revision: Cockerell 1909, Zoologischer Anzriger, 34: p. 565.

Synonyms: Difflugia proteiformis var. symmetrica Wallich, 1863; Difflugia pyriformis var. symmetrica Wallich, 1864; Difflugia symmetrica Wallich, 1864; Assulina assulata Ehrenberg, 1871; Assulina leptolepis Ehrenberg, 1871; Difflugia assulata Ehrenberg, 1871; Difflugia carolensis Ehrenberg, 1871; Quadrula symmetrica Schulze, 1875; Nebela (Quadrulella) symmetrica Deflandre, 1936.

Description: Shell colourless, transparent, ovoid or pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture; laterally compressed, with oval transverse section (Fig. 81 A-E); composed of quadrangular shell-plates with different size, smaller near the aperture, usually arranged in rows (Fig. 81 D-F, I). Aperture terminal, oval, slightly convex frontally and concave laterally, bordered by a thin collar of organic cement (Fig. 81 E-H). Cytoplasm granular, fills about two-thirds of the shell, with numerous food vacuoles; one large ovular nucleus and numerous small nucleoli; pseudopodia usually one or two, long, digitiform, fast moving (Fig. 81 A, C).

Notes: Besides the nominal species, the infrasubspecific taxon Quadrulella symmetrica var. irregularis Wailes et Penard, 1911 has also been recorded.

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Kosakyan et al. 2012, Bankov et al. 2018).

Quadrulella symmetrica. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 84,5 84,5 4,47 0,67 5,29 72 93 44
Breadth 47,2 47,0 3,68 0,55 7,80 41 59 44
Aperture width 21,7 21,6 1,65 0,25 7,60 19 26 44
Depth 32,3 32,0 4,74 1,01 14,67 22 43 22
Breadth/Length ratio 0,56 0,56 0,04 0,007 7,14 0,47 0,66 44
Aperture/Breadth ratio 0,46 0,46 0,03 0,005 6,52 0,38 0,55 44
Figure 81.

Light (A, C) and scanning electron (B, D-I) micrographs of Quadrulella symmetrica. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen to show granular cytoplasm. (D) Broad lateral view. (E) Narrow lateral view. (F) Apertural view. (G) Close up view of aperture to illustrate its elliptical shape and bordering thin collar of organic cement (H) Lateral view of aperture. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Quadrulella variabilis Kosakyan, Lahr, Mulot, Meisterfeld, Mitchell and Lara, 2016

Original description: Kosakyan et al. 2016b, Cladistics, 32, p. 15, Fig. 2.

Description: Shell colourless, transparent, elongate-pyriform, with sides tapering evenly and gradually from rounded aboral region towards to aperture, sometimes forming long neck; laterally compressed, with oval to ellipsoidal transverse section (Fig. 82 A-F); composed of quadrangular shell-plates with different size, smaller near the aperture, usually arranged in rows (Fig. 82 C-F, I). Aperture terminal, oval, slightly convex frontally and concave laterally, bordered by a thin collar of organic cement (Fig. 82 C-E, G, H). Cytoplasm granular, fills about two-thirds of the shell, with numerous food vacuoles (Fig. 82 A). Pseudopodia usually one or two, long, digitiform, fast moving.

Notes: Quadrulella variabilis differs from Q. symmetrica by the smaller size of the shell and shell-plates and from Q. longicollis by about two times smaller shell and not so well defined long neck.

Ecology: In Sphagnum.

Geographical distribution: Recently described from Switzerland, still unknown.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rila Mts. (Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Quadrulella variabilis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 72,4 72,1 3,02 0,51 4,17 67 80 35
Breadth 38,3 38,9 2,49 0,42 6,50 32 42 35
Aperture width 17,4 17,8 1,11 0,19 6,38 14 19 35
Depth 28,8 28,4 1,24 0,32 4,31 27 31 15
Breadth/Length ratio 0,53 0,54 0,04 0,006 7,55 0,41 0,59 35
Aperture/Breadth ratio 0,45 0,45 0,02 0,004 4,44 0,40 0,54 35
Figure 82.

Light (A) and scanning electron (B-I) micrographs of Quadrulella variabilis. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Broad lateral view of two specimens to show the general shape. (E) Latero-apertural view. (F) Narrow lateral view. (G) Lateral view of aperture. (H) Close up view of aperture to illustrate its elliptical shape and bordering thin collar of organic cement (I) Detail of shell surface showing shape and arrangement of shell-plates.

Heleopera petricola Leidy, 1879

Original description: Leidy 1879, Report of the United States Geological Survey of the Territories, 12, p. 165, Pl. XXVI, figs. 12-20.

Description: Shell transparent, colorless, sometimes brownish or purple, ovoid; with rounded aboral region and almost parallel or slightly convex lateral margins; laterally compressed, elliptical in transverse section (Fig. 83 A-F). Anterior half of the shell smooth and composed of siliceous shell-plates; posterior part rough, covered mainly of small to medium quartz particles, mixed with fragments of diatom frustules (Fig. 83 C-E). Aperture terminal, broad, elliptical, slightly convex, with acute commissures and bordered by a thin collar of organic cement (Fig. 83 E-I). Cytoplasm abundant, fills about two-thirds of the shell, without symbiotic zoochlorellae; one large ovular nucleus and many small nucleoli; encysted specimens frequently seen, cysts round or ovale, brown, with thick organic wall, occupying central region of the shell; pseudopodia numerous, short, digitiform, slow moving. (Fig. 83 A, B).

Ecology: Frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Heleopera petricola. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 97,9 98,2 7,52 1,33 7,68 78 111 32
Breadth 63,3 63,0 6,92 1,22 10,9 51 80 32
Large axis of aperture 35,6 35,3 4,46 0,79 12,5 27 43 32
Depth 43,3 42,9 3,76 0,97 8,68 37 49 15
Breadth/Length ratio 0,6 0,6 0,07 0,01 11,67 0,48 0,78 32
Aperture/Breadth ratio 0,6 0,5 0,08 0,01 13,33 0,41 0,74 32
Figure 83.

Light (A, B) and scanning electron (C-I) micrographs of Heleopera petricola. (A) View of several specimens to illustrate variability in shape and size of the shell. (B) View of encysted specimen. (C-D) Broad lateral view of two specimens showing variability of shell structure. (E) Apertural view to show narrow, closed aperture of encysted specimen. (F) Apertural view showing elliptical aperture with acute commissures. (G) Lateral view of aperture. (H) Close up view of aperture showing the bordering thin collar of organic cement. (I) Portion of shell to show arrangement of particles in anterior part of the shell.

Heleopera rosea Penard, 1890

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 166, Pl. VII, fig. 59 à 78.

Description: Shell transparent, reddish or purple, ovoid, with sides tapering evenly and gradually from rounded aboral region towards to aperture, laterally compressed, elliptical in transverse section (Fig. 84 A-E). Anterior half of the shell smooth and composed of siliceous shell-plates, posterior part rough, covered of small to medium mainly flattish quartz particles (Fig. 84 D-I). Aperture terminal, slightly convex, thin linear slit, bordered by thin transparent band of organic cement, with pronounced acute commissures laterally (Fig. 84 C-G). Cytoplasm abundant, fills about two-thirds of the shell, without symbiotic zoochlorellae; one large ovular nucleus and many nucleoli; encysted specimens frequently seen, cysts round or ovale, brown, with thick organic wall, occupying central region of the shell (Fig. 84 A, C). Pseudopodia numerous, short, digitiform, slow moving.

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Heleopera rosea. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 101,0 102,0 6,55 1,20 6,49 90 116 30
Breadth 69,7 71,0 6,51 1,19 9,34 56 80 30
Large axis of aperture 38,9 39,9 5,59 1,02 14,39 28 49 30
Depth 45,0 44,5 3,23 0,67 7,19 40 51 23
Breadth/Length ratio 0,69 0,68 0,06 0,01 8,60 0,6 0,9 30
Aperture/Breadth ratio 0,56 0,56 0,07 0,07 12,69 0.4 0,7 30
Figure 84.

Light (A, C) and scanning electron (B, D-I) micrographs of Heleopera rosea. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of encysted specimen. (D, E) Broad lateral view of two specimens showing variability of shell structure. (F) Apertural view to show a narrow, closed aperture of encysted specimen. (G) Broad lateral view of aperture showing the bordering thin band of organic cement. (H) Portion of anterior part of the shell to show its smooth surface, composed of siliceous shell-plates. (I) Portion of posterior part of the shell to show its rough surface, covered mainly by flattish quartz particles.

Heleopera sphagni (Leidy, 1874)

Original description: Leidy 1874b, Proceedings of the Academy of Natural Sciences of Philadelphia, 26, p. 157.

Synonyms: Difflugia (Nebela) sphagni Leidy, 1874; Nebela sphagni Leidy, 1876; Heleopera picta Leidy, 1879.

Description: Shell transparent, yellow or brown, ovoid, with sides tapering evenly and gradually from rounded aboral region towards to aperture, laterally compressed, with elliptical transverse section (Fig. 85 A-E). Anterior half of the shell smooth, composed of siliceous shell-plates, posterior part rough, covered of small to medium mainly flattish quartz particles (Fig. 85 A-D). Aperture terminal, broad, elliptical, slightly convex, laterally concave, with acute commissures, bordered by thin collar of organic cement (Fig. 85 A-G). Cytoplasm does not fills the whole shell, always fulfilled with symbiotic zoochlorellae; encysted specimens frequently seen, cysts round, with zoochlorellae and thick organic wall, occupying central region of the shell. Pseudopodia numerous, long, digitiform, sometimes bifurcated, slow moving.

Ecology: In Sphagnum, very rare in Bulgaria.

Geographical distribution: Probably cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993).

Heleopera sphagni. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 107,1 106,4 3,32 0,78 3,10 103 117 18
Breadth 76,4 74,8 4,01 0,95 5,25 73 89 18
Large axis of aperture 45,2 43,7 3,68 0,87 8,14 42 55 18
Depth 44,3 43,7 2,00 0,53 4,51 42 49 14
Breadth/Length ratio 0,7 0,7 0,02 0,005 2,86 0,68 0,76 18
Aperture/Breadth ratio 0,6 0,6 0,02 0,005 3,33 0,56 0,64 18
Figure 85.

Scanning electron micrographs of Heleopera sphagni. (A-D) Broad lateral view of four specimens to illustrate variability in shape and structure of the shell. (E) Narrow lateral view. (F) Close up view of aperture to show a narrow elliptical aperture. (G) Lateral view showing acute commissures of aperture. (H, I) Details of shell surface showing differences in shape and arrangement of shell-plates.

Heleopera sylvatica Penard, 1890

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 168, Pl. VII, fig. 79 à 94.

Description: Shell transparent, colorless or yellowish, ovoid, with sides tapering evenly and gradually from rounded aboral region towards to aperture (Fig. 86 A-D); laterally compressed, with oval transverse section (Fig. 86 E-G); composed of different in size circular, overlapping, siliceous shell-plates, usually arranged regularly to give smooth outline (Fig. 86 D-G, I); sometimes with attached few siliceous plates on the margin of aboral region (Fig. 86 B, D, F). Aperture terminal, broad, elliptical, slightly convex, laterally concave, with acute commissures, bordered by thin collar of organic cement (Fig. 86 D-H). Cytoplasm abundant, fills almost whole shell, without symbiotic zoochlorellae; one large ovular nucleus, few small nucleoli; encysted specimens frequently seen, cysts large, round or oval, dark-brown, with thick organic wall, occupying central region of the shell; pseudopodia numerous, usually six to eight, long, digitiform, slow moving (Fig. 86 A, C).

Ecology: Frequent in soil mosses and litter in deciduous forests, very rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov 2005, Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990).

Heleopera sylvatica. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 97.8 98.2 5.51 0.92 5.64 88 108 36
Breadth 63.2 63.2 3.96 0.66 6.27 54 74 36
Large axis of aperture 38.3 37.6 4.56 0.76 11.92 30 48 36
Depth 42.2 42.3 1.31 0.35 3.10 40 44 14
Breadth/Length ratio 0.65 0.64 0.04 0.006 6.02 0.6 0.7 36
Aperture/Breadth ratio 0.61 0.61 0.06 0.01 10.11 0.5 0,7 36
Figure 86.

Light (A, C) and scanning electron (B, D-I) micrographs of Heleopera sylvatica. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing granular cytoplasm and numerous pseudopodia. (D) Broad lateral view showing shape and regular arrangement of shell-plates. (E) Apertural view to show a narrow, elliptical aperture. (F) Lateral view showing acute commissures of the aperture. (G) Latero-apertural view. (H) Close up view of elliptical aperture to show the bordering thin collar of organic cement. (I) Detail of shell surface showing shape and arrangement of shell-plates.

Phryganella acropodia (Hertwig and Lesser, 1874) Hopkinson, 1909

Original description: Hertwig and Lesser 1874, Archiv für mikroskopische Anatomie, 10, p. 107, Taf. II, fig. 6; Last revision: Cash and Hopkinson 1909, The British Freshwater Rhizopoda and Heliozoa. Vol. II. Rhizopoda, p. 74, Pl. XX, figs. 13, 14.

Synonyms: Difflugia acropodia Hertwig and Lesser, 1874.

Description: Shell yellowish or brownish, circular in apertural and aboral views, hemispherical in lateral view (Fig. 87 A-F); composed mainly of small to medium pieces of quartz, so arranged to give a well defined and regular outline, with rough aboral surface and smooth apertural surface (Fig. 87 C-F). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 87 E, F, I). Aperture circular, central, slightly or non invaginated, with rim of organic cement (Fig. 87 C, D, G).

Ecology: Frequent in soils, mosses and forest litter, rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Phryganella acropodia. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 37,7 37,5 2,15 0,37 5,70 34 43 33
Diameter of aperture 16,4 16,7 1,78 0,33 10,85 14 20 29
Depth 33,4 33,0 2,58 0,47 7,72 29 38 30
Depth/Diameter ratio 0,44 0,45 0,05 0,009 11,36 0,35 0,52 29
Aperture/Diameter ratio 0,88 0,89 0,06 0,012 6,82 0,73 0,99 30
Figure 87.

Light (A) and scanning electron (B-I) micrographs of Phryganella acropodia. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C-D) Apertural view of two specimens showing general shape. (E) Lateral view. (F) Dorsal view. (G) Close up view of aperture to illustrate its smooth rim and circular outline. (H, I) Details of lateral and dorsal side of the shell to illustrate its rough surface, covered with large pieces of quartz.

Phryganella hemisphaerica (Penard, 1890) Penard, 1902

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 169, Pl. VII, fig. 108 à 114; Last revision: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 421, fig. 1 à 5.

Synonyms: Pseudodifflugia hemisphaerica Penard, 1890; Difflugia globulosa Leidy, 1879 (in part).

Description: Shell yellowish or brownish, circular in apertural and aboral views, hemispherical in lateral view (Fig. 88 A-F); composed mainly of small to medium pieces of quartz, mixed with diatom frustules, with rough surface (Fig. 88 C-I). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 88 D-I). Aperture large, circular, central, non invaginated, with thin collar of organic cement (Fig. 88 C-E, H, I).

Ecology: Common in standing freshwater basins, among aquatic vegetation and in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Phryganella hemisphaerica. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 52,2 52,0 5,11 0,93 9,79 42 60 30
Diameter of aperture 31,8 31,6 3,70 0,68 11,64 24 42 30
Depth 31,5 31,1 4,89 0,89 15,52 21 41 30
Aperture/Diameter ratio 0,61 0,61 0,06 0,01 9,84 0,50 0,79 30
Depth/Diameter ratio 0,61 0,60 0,09 0,02 14,75 0,41 0,85 30
Figure 88.

Light (A, B) and scanning electron (C-I) micrographs of Phryganella hemisphaerica. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D, E) Apertural view of two specimens showing general shape. (F) Dorsal view. (G) Lateral view. (H) Close up view of aperture to illustrate its thin collar and circular outline. (I) Details of lateral side of the shell to illustrate its rough surface, covered with large pieces of quartz and diatom frustules.

Phryganella nidulus Penard, 1902

Original description: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 419, fig. 1 à 4 (p. 420).

Synonyms: Difflugia globulosa Leidy, 1879 (in part).

Description: Shell yellowish or brownish, opaque, large, circular in apertural and aboral views, hemispherical in lateral view (Fig. 89 A-E); composed mainly of small to medium pieces of quartz, mixed with diatom frustules, with rough surface (Fig. 89 B-I). Shell components usually in close contact with each other, organic cement rarely visible between particles (Fig. 89 F-I). Aperture large, about two-thirds of the shell-diameter, circular, central, slightly invaginated, surrounded by quartz particles, with irregular outline (Fig. 89 B, C, F, G).

Ecology: Frequent in benthos of lakes and reservoirs, less frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (Todorov 2004, 2005, Bankov et al. 2018); Vitosha Mts. (Pateff 1924).

Phryganella nidulus. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Diameter 153,5 151,3 9,75 2,08 6,35 140 174 22
Diameter of aperture 88,3 88,3 7,46 1,59 8,45 72 99 22
Depth 85,7 87,4 7,17 1,65 8,37 71 95 19
Aperture/Diameter ratio 0,58 0,57 0,031 0,007 5,34 0,49 0,63 22
Depth/Diameter ratio 0,56 0,56 0,027 0,006 4,82 0,49 0,59 19
Figure 89.

Light (A, B) and scanning electron (C-I) micrographs of Phryganella nidulus. (A) View of several specimens to illustrate variability in shape and size of the shell. (B, C) Apertural view of two specimens showing general shape and large aperture. (D) Dorsal view. (E) Lateral view. (F, G) Close up view of apertural rim to illustrate its denticulate outline. (H, I) Details of dorsal side of the shell to illustrate its rough surface, covered with large pieces of quartz and diatome frustules.

Argynnia dentistoma (Penard, 1890)

Original description: Penard 1890, Mémoires de la Société de Physique et d’Histoire Naturelle de Genève, 31, p. 162, Pl. VI, fig. 98 à 100, Pl. VII, fig. 1 à 5.

Synonyms: Nebela dentistoma Penard, 1890; Nebela crenulata Penard, 1893; Nebela collaris Leidy, 1879 (in part).

Description: Shell colourless, transparent, ovoid or pyriforme, with sides tapering evenly and gradually from rounded aboral region towards to aperture, sometimes forming short neck (Fig. 90 A-D); laterally compressed, with oval transverse section; without lateral margins and lateral pores (Fig. 90 E-F); composed of thickened, oval, circular or irregular polygonal, do not overlapping shell-plates, embedded by porous organic cement (Fig. 90 D- I). Aperture oval, denticulated, surrounded by shell-plates, without collar of organic cement (Fig. 90 C-H). Cytoplasm granular, does not fills whole shell; one large ovular nucleus with numerous small nucleoli; pseudopodia usually few, large, not very long, fast moving.

Notes: The species has been recorded as nominal species, as synonyms N. dentistoma and N. crenulata, as well as infrasubspecific taxa Nebela dentistoma var. oblonga.

Ecology: Common in Sphagnum, as well as in soil mosses and litter in deciduous forests.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Argynnia dentistoma. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 108.4 111.3 15.84 2.80 14.61 82 137 32
Breadth 78.6 78.9 9.25 1.63 11.77 60 97 32
Large axis of aperture 26.4 26.4 4.59 0.81 17.38 19 37 32
Depth 49.6 50.9 8.75 1.86 17.65 32 66 22
Breadth/Length ratio 0.73 0.72 0.06 0.011 8.26 0.6 0.9 32
Aperture/Breadth ratio 0.34 0.33 0.04 0.007 12.32 0.3 0.4 32
Figure 90.

Light (A, C) and scanning electron (B, D-I) micrographs of Argynnia dentistoma. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Broad lateral view. (E) Apertural view. (F) Narrow lateral view. (G) Broad lateral view of apertural region. (H) Close up view of aperture showing its oval outline. (I) Detail of shell surface showing shape and arrangement of shell-plates, and porous structure of the organic cement.

Argynnia vitraea (Penard, 1899)

Original description: Penard 1899, Revue Suisse de Zoologie, 7, p. 43, Pl. 4, fig. 5 à 16.

Synonyms: Nebela vitraea Penard, 1899.

Description: Shell colourless, transparent, ovoid or pyriforme, with sides tapering evenly and gradually from rounded aboral region towards to aperture (Fig. 91 A-D); laterally compressed, with oval transverse section; without lateral margins and lateral pores (Fig. 91 E-F); composed of thickened, oval, circular or angular shell-plates, adhering at their edges, rarely overlapping, embedded by porous organic cement (Fig. 91 D- I). Aperture oval, denticulated, surrounded by ring of small irregularly-shaped sand-grains (Fig. 91 D-G). Cytoplasm granular, does not fills the whole shell; one large ovular nucleus with numerous small nucleoli; pseudopodia usually few, in stage of active movement only one, large, long and fast moving.

Notes: Argynnia vitraea is too close to A. dentistoma and differs difficultly from it mainly by the larger size and by the arrangement of shell-plates, which are usually touching tightly and sometimes have small particles on their borders. The species has been recorded in both as nominal species and as synonym N. vitraea.

Ecology: Frequent in wet Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005); Vitosha Mts. (Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995).

Argynnia vitraea. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 177.3 175.4 9.84 1.54 5.55 148 198 41
Breadth 158.5 162.8 15.01 2.34 9.47 107 186 41
Large axis of aperture 46.4 44.8 6.18 0.97 13.31 37 60 41
Depth 93.7 94.2 9.79 2.45 10.44 76 108 16
Breadth/Length ratio 0.89 0.90 0.06 0.01 7.26 0.62 0.98 41
Aperture/Breadth ratio 0.30 0.29 0.05 0.007 16.20 0.2 0.4 41
Figure 91.

Light (A, C) and scanning electron (B, D-I) micrographs of Argynnia vitraea. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C, D) Broad lateral view. (E) Apertural view. (F) Narrow lateral view. (G) Close up view of aperture showing its oval and irregularly dentate outline. (H) Detail of shell surface showing shape and arrangement of shell-plates, and porous structure of the organic cement. (I) Close up view of porous organic cement.

Awerintzewia cyclostoma (Penard, 1902) Schouteden, 1906

Original description: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 390, fig. 1 à 6 (p. 391); Last revision: Schouteden 1906, Annales de Biologie Lacustre, 1 (3), p. 357.

Synonyms: Heleopera cyclostoma Penard, 1902.

Description: Shell brownish or purple, opaque, ovoid, with sides tapering evenly and gradually from rounded aboral region towards to aperture, laterally compressed, oval in transverse section (Fig. 92 A-G); anterior half of the shell smooth, composed of flattish, siliceous shell-plates; posterior part rough, covered mainly of larger pieces of quartz (Fig. 92 D-F). Aperture terminal, small, oval, truncate, without lateral commissures, bordered by thin collar of organic cement, with characteristic double margins in the apertural region (Fig. 92 A-H).

Notes: The species has been recorded in both as nominal species and as synonym H. cyclostoma (Rhodopes Mts.) .

Ecology: Frequent in calcareous soils and mosses, rare in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (new data).

Awerintzewia cyclostoma. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 162.0 161.7 8.07 1.33 4.98 146 178 37
Breadth 111.4 110.7 5.56 0.91 4.99 98 121 37
Large axis of aperture 41.8 41.2 5.21 0.86 12.46 31 54 37
Depth 81.5 81.9 5.73 1.81 7.03 73 90 10
Breadth/Length ratio 0.69 0.69 0.04 0.006 5.11 0.6 0.8 35
Aperture/Breadth ratio 0.38 0.38 0.05 0.008 12.83 0.3 0.5 36
Figure 92.

Light (A, C) and scanning electron (B, D-I) micrographs of Awerintzewia cyclostoma. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C-E) Broad lateral view of three specimens to show general shape. (F) Narrow lateral view. (G) Apertural view showing oval sross section of the shell and small oval aperture. (H) Close up view of aperture showing its oval outline and bordering rim of organic cement. (I) Portion of shell to show arrangement of flattish particles in the anterior part of the shell.

Lagenodifflugia bryophila (Penard, 1902) Ogden, 1987

Original description: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 324, figs. 1-4; Last revision: Ogden 1987, Bulletin of the British Museum (Natural History), Zoology series, 52 (1), p. 15.

Synonyms: Pontigulasia bryophila Penard, 1902; Pontigulasia bryophila var. elachys Jung, 1942; Pontigulasia varadi Godeanu, 1972; Zivkovicia bryophila (Penard, 1902) Ogden, 1983.

Description: Shell yellowish-brownish, opaque, elongated-pyriform, with pronounced constriction at place of internal diaphragm, forming distinct neck about one-third of the body length and ovoid main body with circular transverse section (Fig. 93 A-D); covered mainly of small to medium quartz particles and occasionally with larger particles, with rough surface (Fig. 93 C-H). Shell components usually in close contact with each other, only small areas of organic cement are seen as network of rings with perforated centre; each ring of about 500-750 nm in diameter has an internal network with ten to fourteen irregular pores of about 40-70 nm in diameter (Fig. 93 I). External aperture roughly circular, with notched or tooth-like appearance, surrounded by regularly arranged small quartz particles; internal diaphragm constructed of small particles as part of shell wall, with single central opening of about 12-14 μm (Fig. 93 E-G). Cytoplasm granular, fills almost whole shell, without symbiotic zoochlorellae; one large ovular nucleus with numerous small nucleoli; pseudopodia usually two to four, long and fast moving (Fig. 93 A-B).

Notes: The species has been recorded in both as nominal species and as synonym P. bryophila (Rhodopes Mts., Rila Mts., Vitosha Mts.).

Ecology: Frequent in Sphagnum and freshwater habitats.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1990, Todorv 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Lagenodifflugia bryophila. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 115.6 116.0 6.36 0.96 5.50 101 132 44
Breadth 56.8 57.0 2.56 0.39 4.52 53 63 44
Diameter of aperture 23.4 23.7 2.65 0.40 11.33 18 29 44
Breadth/Length ratio 0.49 0.49 0.03 0.004 5.38 0.5 0.6 44
Aperture/Breadth ratio 0.41 0.41 0.05 0.007 11.14 0.3 0.5 44
Figure 93.

Light (A, B) and scanning electron (C-I) micrographs of Lagenodifflugia bryophila. (A) View of many specimens to illustrate variability in shape and size of the shell. (B) View of live specimen showing long endolobopodia and granular cytoplasm (C, D) Lateral view of two individuals to show a general shape. (E) Apertural view. (F) Close up view of aperture. (G) Close up view of internal opening. (H) Portion of shell to show arrangement of particles and rough surface of the shell. (I) Detail of organic cement network.

Lagenodifflugia vas (Leidy, 1874) Medioli and Scott, 1983

Original description: Leidy 1874a, Proceedings of the Academy of Natural Sciences of Philadelphia, 26, p. 155; Last revision: Medioli and Scott 1983, Cushman Foundation for Foraminiferal Research, Special Publication, 21, 33, Pl. 2, Figs 18–23, 27, 28.

Synonyms: Difflugia vas Leidy, 1874; Difflugia pyriformis var. vas Leidy, 1879; Pontigulasia vas (Leidy) Schouteden, 1906; Zivkovicia vas (Leidy, 1874) Ogden, 1983 (in part).

Description: Shell yellowish-brownish, opaque, pyriform, with not always conspicuous constriction at place of internal diaphragm, dividing shell of two unequal parts, smaller wedge-shaped neck, about one-third of the body length, and larger rounded main body, with circular transverse section (Fig. 94 A-F); covered mainly of small to medium quartz particles, often with constriction more or less hidden by larger particles (Fig. 94 B, D-F). Shell components usually in close contact with each other, only small areas of organic cement are seen infrequently as network with mesh of about 450-600 nm in diameter and walls 150-200 nm thick; each mesh perforated with smaller openings of different size (Fig. 94 H, I). External aperture roughly circular, with notched or tooth-like appearance, surrounded by regularly arranged small quartz particles; internal diaphragm constructed of small particles as part of shell wall, with single central opening of about 25-30 μm (Fig. 94 E-G). Cytoplasm granular, fills almost whole shell, without symbiotic zoochlorellae; one large ovular nucleus, few nucleoli Pseudopodia usually two to four, long and fast moving (Fig. 94 A, C).

Ecology: Frequent in Sphagnum and freshwater habitats.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Bankov et al. 2018); Vitosha Mts. (Bankov et al. 2018).

Lagenodifflugia vas. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 176.4 175.0 9.20 1.60 5.21 157 196 33
Breadth 111.1 113.0 7.30 1.27 6.57 96 127 33
Diameter of aperture 37.1 36.0 3.64 0.63 9.80 32 46 33
Breadth/Length ratio 0.63 0.62 0.05 0.008 7.30 0.6 0.8 33
Aperture/Breadth ratio 0.33 0.34 0.03 0.006 9.57 0.3 0.4 33
Figure 94.

Light (A, C) and scanning electron (B, D-I) micrographs of Lagenodifflugia vas. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing long endolobopodia and granular cytoplasm. (D, E) Lateral view of two individuals to show a general shape. (F) Apertural view. (G) Close up view of internal opening. (H) Portion of shell to show arrangement of particles and rough surface of the shell. (I) Detail of organic cement network.

Pontigulasia rhumbleri Hopkinson, 1919

Original description: Cash et al. 1919, The British Freshwater Rhizopoda and Heliozoa. Vol. IV, p. 49, Pl. LXIII, figs. 1, 2.

Synonims: Pontigulasia compressa Rhumbler, 1896; (non Pontigulasia compressa (Carter, 1864).

Description: Shell colorless or yellowish, transparent, pyriform, rounded aborally and tapering evenly towards to the aperture, without forming distinct neck (Fig. 95 A-C); laterally compressed, with oval transverse section (Fig. 95 D); composed mainly of flattish pieces of quartz and diatom frustules, with relatively smooth appearance (Fig. 95 A-C). Shell components usually in close contact with each other; only small areas of organic cement are seen as either individual rings or as network with mesh of about 500 nm in diameter and walls 250-300 nm thick; each mesh enclosure covered by inner strands of cement which form smaller mesh with different size (Fig. 95 H, I). External aperture roughly circular, surrounded by small quartz particles and diatom frustules (Fig. 95 D, E). Internal dividing bridge ribbon-shaped, placed centrally at short distance from aperture, evenly widening towards to its connects with broader sides of the shell, leaving large openings on either side (Fig. 95 F). Cytoplasm granular, does not fills the whole shell; cell attached to the shell wall with clearly visible short epipodes; one large ovular nucleus; pseudopodia usually one or two, sometimes numerous, large, long, fast moving (Fig. 95 A, B).

Notes: The species has been recorded in both as nominal species and as synonym P. compressa (Rhodopes Mts., Rila Mts., Vitosha Mts.).

Ecology: Frequent in Sphagnum and standing freshwater bodies, among submerged aquatic vegetation.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Todorov 2004, 2005); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924).

Pontigulasia rhumbleri. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 116.3 116.9 8.86 1.52 7.62 101 139 34
Breadth 79.5 80.7 6.42 0.94 8.08 62 92 47
Diameter of aperture 29.3 29.4 3.03 0.44 10.35 23 37 47
Depth 65.7 64.7 5.40 1.44 8.22 60 76 14
Breadth/Length ratio 0.67 0.68 0.05 0.009 8.02 0.6 0.8 34
Aperture/Breadth ratio 0.37 0.36 0.04 0.006 10.42 0.3 0.5 47
Figure 95.

Light (A, B) and scanning electron (C-I) micrographs of Pontigulasia rhumbleri. (A) View of many specimens to illustrate variability in shape and size of the shell. (B) View of live specimen to show a single long endolobopodia. (C) Broad lateral view showing general shape. (D) Apertural view (E) View of aperture showing its irregular outline and surrounding angular particles of quartz. (F) Close up view of internal opening. (G) Portion of shell surface. (H, I) Details of organic cement network.

Zivkovicia compressa (Carter, 1864) Ogden, 1983

Original description: Carter 1864, Annals and Magazine of Natural History, 13, p. 22, Pl. I, figs. 5, 6; Last revision: Ogden 1983, Protistologica, 19, p. 226, Figs 18–29.

Synonims: Difflugia compressa Carter, 1864; Difflugia pyriformis var. vas sub- var. bigibbosa Penard, 1899; Pontigulasia bigibbosa Penard, 1902

Description: Shell yellowish-brownish, opaque, pyriform, with characteristic V-shaped notch on the shell, indicating place of internal diaphragm; divided into two unequal parts, smaller wedge-shaped neck, and larger rounded main body; laterally compressed, with oval transverse section (Fig. 96 A-F); covered mainly of small to medium quartz particles, mixed with several angular large particles, with rough surface (Fig. 96 B, D-F). Shell components usually in close contact with each other, small areas of organic cement are seen as network with mesh of about 500-650 nm in diameter and walls 150-250 nm thick; each mesh perforated by about 12-14 smaller openings of different size (Fig. 96 H, I). External aperture broadly-oval, surrounded by regularly arranged small quartz particles; internal diaphragm constructed of small particles as part of shell wall, with two internal openings on either narrow sides of the shell, placed close to the shell wall; internal openings are not visible through the external aperture when viewed directly and are seen clearly when shell is tilted to either side (Fig. 96 G). Cytoplasm granular, fills almost whole shell, without symbiotic zoochlorellae; pseudopodia usually two to four, long, fast moving (Fig. 96 A, C).

Ecology: Frequent in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Golemansky 1974, Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Zivkovicia compressa. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 199.6 195.0 16.01 2.24 8.02 173 248 51
Breadth 140.5 141.0 11.99 1.68 8.53 99 166 51
Large axis of aperture 45.6 44.8 4.96 0.69 10.89 35 59 51
Depth 106.8 105.3 7.25 1.07 6.79 86 123 46
Breadth/Length ratio 0.71 0.71 0.05 0.007 7.51 0.5 0.8 51
Aperture/Breadth ratio 0.33 0.32 0.04 0.005 10.99 0.3 0.4 51
Figure 96.

Light (A, C) and scanning electron (B, D-I) micrographs of Zivkovicia compressa. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing endolobopodia. (D, E) Broad lateral views. (F) Apertural view (G) Apertural view of tilted specimen to show one of the internal openings. (H) Portion of shell showing its rough surface. (I) Detail of organic cement network.

Zivkovicia spectabilis (Penard, 1902) Ogden, 1987

Original description: Penard 1902, Faune Rhizopodique du Bassin du Léman, p. 318, fig. 1-9 (p. 319); Last revision: Ogden 1987, Bulletin of the British Museum (Natural History), Zoology series, 52 (1), p. 15.

Synonyms: Pontigulasia spectabilis Penard, 1902; Zivkovicia vas (Leidy, 1874) Ogden, 1983 (in part).

Description: Shell yellowish-brownish, opaque, pyriform, with pronounced constriction at place of internal diaphragm, dividing shell of two parts, almost equal in length - tubular or wedge-shaped neck, slightly convex in middle, and spherical main body; uncompressed, with circular transverse section (Fig. 97 A-F); covered mainly of small to medium quartz particles and occasionally with fragment of diatom frustules, with rough surface (Fig. 97 D-F). Shell components usually in close contact with each other, only small areas of organic cement are seen infrequently as network with mesh of about 600-950 nm in diameter, without well pronounced walls; each mesh is covered by inner strands of cement forming fine network of about 15-25 openings with different size (Fig. 97 H, I). External aperture roughly circular, surrounded by irregularly arranged small to medium quartz particles; internal diaphragm constructed of small particles as part of shell wall, with two internal openings, placed close to the shell wall and partly visible through the external aperture when viewed directly (Fig. 97 D-G). Cytoplasm granular, completely fills rounded body, without symbiotic zoochlorellae; one large ovular nucleus, few nucleoli; pseudopodia usually one to three, long, fast moving (Fig. 97 A, C).

Notes: The species has been recorded in both as nominal species and as synonym P. spectabilis (Rhodopes Mts.).

Ecology: Frequent in freshwater habitats and in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky 1968); Rila Mts. (Todorov 2004).

Zivkovicia spectabilis. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 114.5 115.5 6.45 1.02 5.63 102 131 40
Breadth 70.3 70.5 4.67 0.74 6.64 56 78 40
Diameter of aperture 26.1 26.0 2.60 0.41 9.96 20 32 40
Breadth/Length ratio 0.61 0.61 0.04 0.006 5.99 0.5 0.7 40
Aperture/Breadth ratio 0.37 0.36 0.03 0.005 9.17 0.3 0.4 40
Figure 97.

Light (A, C) and scanning electron (B, D-I) micrographs of Zivkovicia spectabilis. (A, B) View of many specimens to illustrate variability in shape and size of the shell. (C) View of live specimen showing long endolobopodia. (D, E) Lateral view of two individuals to show a general shape. (F) Apertural view. (G) Close up view of internal openings. (H) Portion of shell to show arrangement of quartz particles and rough surface. (I) Detail of organic cement network.

Archerella flavum (Archer, 1877) Loeblich and Tappan, 1961

Original description: Archer 1877, Quarterly Journal of Microscopical Science, new series, 17, p. 336, Pl. XXI, Fig. 9; Last revision: Loeblich and Tappan 1961, Proceedings of the Biological Society of Washington, 74, p. 217.

Synonyms: Ditrema flavum Archer, 1877; Amphitrema flavum Archer, 1877.

Description: Shell yellowish-brownish, transparent, elliptical, with broadly rounded edges; laterally compressed, with oval to elliptical transverse section; on each of the narrow edges is located one small oval aperturte (Fig. 98 A-F); entirely composed of organic matter, smooth. Apertures two, small, oval, bordered by thin collar (Fig. 98 H, I). Cytoplasm granular, fills whole shell, always fullfiled with numerous symbiotic zoochlorellae; one large vesicular nucleus placed centraly in the cell, with one small nucleolus; pseudopodia rarely visible, usually two or three, thin, long, fast moving (Fig. 98 A, B).

Notes: The species has been recorded as synonym Amphitrema flavum (Rhodopes Mts., Vitosha Mts.).

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Archerella flavum. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 55.9 56.3 4.55 0.82 8.13 46 64 31
Breadth 32.2 31.9 2.7 0.50 8.47 26 39 31
Large axis of aperture 9.1 9.3 1.40 0.25 15.43 6 12 31
Depth 19.9 18.8 3.69 0.87 18.55 14 28 18
Aperture/Breadth ratio 0.58 0.57 0.06 0.010 9.82 0.5 0.7 31
Figure 98.

Light (A, B) and scanning electron (C-I) micrographs of Archerella flavum. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D-F) Broad lateral view of three individuals to show the general shape and smooth shell surface. (G) Narrow lateral view. (H) Apertural view to show small aperture. (I) Close up view of aperture showing its oval outline and thin apertural collar.

Assulina muscorum Greeff, 1888

Original description: Greeff 1888, Sitzungsberichte der Gesellschaft zur Beförderung der gesammten Naturwissenschaften zu Marburg, 3, pp. 117-118.

Synonyms: Assulina seminulum Leidy, 1879 (in part); Assulina minor Penard, 1890.

Description: Shell yellowish-brownish, in young individuals colourless; ovoid, laterally compressed, with elliptical transverse section (Fig. 99 A-G); composed of small, oval, overlapping shell-plates of about 4,7-5,2 x 2,1-2,3 μm, regularly arranged in 12-15 alternating diagonal rows, rarely irregularly arranged (Fig. 99 D-G, I). Aperture oval or lenticular, surrounded by haphazardly arranged shell-plates, bordered by thin membrane of organic cement, with irregularly-dentate margin (Fig. 99 F-H). Cytoplasm hyaline, with many granules concentrated in the central region, fills almost whole shell; one vesicular nucleus containing single small nucleolus, placed posteriorly in the cell (Fig. 99 B). Pseudopodia few, fine, long, straight, rarely observed.

Notes: Assulina muscorum differs from A. seminulum by the shape and size of the shell and by twice smaller shell-plates.

Ecology: Common in Sphagnum and aerophilic mosses, less frequent in soils.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Assulina muscorum. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 45.7 46.1 4.32 0.78 9.46 37 55 31
Breadth 34.4 33.7 2.99 0.54 8.71 29 42 31
Large axis of aperture 11.2 11.1 1.69 0.30 15.08 8 15 31
Depth 18.7 18.5 1.46 0.32 7.80 16 22 20
Breadth/Length ratio 0.76 0.75 0.07 0.012 8.74 0.6 0.9 31
Aperture/Breadth ratio 0.33 0.32 0.04 0.008 13.51 0.3 0.5 31
Figure 99.

Light (A, B) and scanning electron (C-I) micrographs of Assulina muscorum. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D-F) Broad lateral view of three individuals to show general shape and regular arrangement of shell-plates. (G) Latero-apertural view of aperture to illustrate its lenticular-oval shape. (H) Close up view of apertural region showing arrangement of apertural-plates and thin border of organic cement. (I) Detail of shell surface to show overlapping, oval shell-plates.

Assulina seminulum (Ehrenberg, 1848) Leidy, 1879

Original description: Ehrenberg 1848b, Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königliche Preussischen Akademie der Wissenschaften zu Berlin, 13, p. 379; Last revision: Leidy 1879, Report of the United States Geological Survey of the Territories, 12, p. 225, Pl. XXXVII, figs. 18-25.

Synonyms: Difflugia seminulum Ehrenberg, 1848; Difflugia Assulina seminulum Ehrenberg, 1871; Difflugia semen Ehrenberg, 1871; Euglypha brunnea Leidy, 1874; Euglypha seminulum Leidy, 1878.

Description: Shell yellowish-brownish, in very young individuals colourless; ovoid or sub-spherical, laterally compressed, with elliptical transverse section (Fig. 100 A-F); composed of oval, overlapping shell-plates of about 9-10 x 4-5 μm, regularly arranged in 16-18 alternating diagonal rows, rarely irregularly arranged (Fig. 100 B-F, I). Shell-plates usually overlapped from aperture to the aboral region, but in some individuals are imbricated inversely, from aboral region to the aperture (Fig. 100 C). Aperture oval or lenticular, surrounded by evenly spaced or haphazardly arranged shell-plates, bordered by a thin membrane of organic cement, with irregularly-dentate margin (Fig. 100 D-G). Cytoplasm granular, does not fills entirely shell; one large nucleus placed posteriorly in the cell. Pseudopodia few, fine, long, straight, rarely observed.

Ecology: Common in Sphagnum, less frequent in aerophilic mosses and soils.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Golemansky and Todorov 1993, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1990, Bankov et al. 2018).

Assulina seminulum. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 79.4 80.2 5.45 0.99 6.83 65 91 30
Breadth 63.1 63.1 6.08 1.11 9.63 44 77 30
Large axis of aperture 21.2 20.3 4.05 0.74 19.10 15 35 30
Depth 32.4 32.8 1.90 0.41 5.86 28 36 21
Breadth/Length ratio 0.79 0.80 0.05 0.010 6.56 0.7 0.9 30
Aperture/Breadth ratio 0.34 0.34 0.06 0.010 16.68 0.2 0.5 30
Figure 100.

Light (A, C) and scanning electron (B, D-I) micrographs of Assulina seminulum. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D) Broad lateral view showing general shape and regular arrangement of shell-plates. (E) Narrow lateral view. (F) Apertural view. (G) Close up view of aperture to illustrate shape of aperture, arrangement of apertural-plates and thin border of organic cement. (H) Lateral view of apertural region (I) Detail of shell surface to show overlapping, oval shell-plates.

Euglypha bryophila Brown, 1911

Original description: Brown 1911, Journal of the Linnean Society of London, Zoology, 32, no 212, p. 82, Pl. 9, figs. 14-15.

Synonyms: Euglypha α Vejdovsky, 1882; Euglypha cristata Penard, 1890 (in part).

Description: Shell colorless, transparent, elongate-oviform, slightly compressed and oval in transverse section; apex of the aboral region bears a tuft of long, thin and tapering siliceous spines, three to nine in number (Fig. 101 A-E, H); composed of oval, slightly overlapping shell-plates of about 8 x 4 μm, arranged in eight to nine longitudinal and eleven to thirteen transverse alternating rows (Fig. 101 B-E, I). Aperture circular, surrounded by seven to nine oval and denticulate apertural plates with pronounced three-lobed thickening at the denticulate margin and elongated lobe at the posterior margin; each apertural plate with large median tooth and two smaller lateral teeth on each side (Fig. 101 G-H). Cytoplasm fills about two-thirds of the shell; one small vesicular nucleus with central nucleolus. Pseudopodia one or a few, thin, long, directed straight ahead, fast moving.

Ecology: Frequent in mosses, rarely in forest litter, soils and Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1990, Bankov et al. 2018).

Euglypha bryophila. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 49.1 50.0 4.94 0.9 10.07 34 56 30
Breadth 21.3 21.7 2.24 0.41 10.52 14 24 30
Diameter of aperture 8.8 8.7 1.28 0.23 14.49 6 11 30
Depth 16.4 16.7 1.79 0.43 10.96 11 18 17
Length of spines 11.4 10.7 2.69 0.52 23.69 7 19 27
Breadth/Length ratio 0.44 0.43 0.04 0.007 8.72 0.4 0.5 30
Aperture/Breadth ratio 0.42 0.40 0.05 0.01 13.08 0.3 0.5 30
Figure 101.

Light (A) and scanning electron (B-I) micrographs of Euglypha bryophila. (A) View of many specimens to illustrate variability in shape and size of the shell. (B, C) Broad lateral view of two specimens to show symmetrical arrangement of shell plates and disposition of spines in the centre of the aboral region. (D) Narrow lateral view. (E) Apertural view. (F) View of aboral region showing spines and their attachment to the shell. (G) Close up view of aperture. (H) View of apertural plates illustrating pronounced three-lobed thickening at the anterior margin and elongated lobe at the posterior margin (I) Detail of shell surface to show overlapping shell plates.

Euglypha ciliata (Ehrenberg, 1848), Leidy, 1878

Original description: Ehrenberg 1848b, Bericht über die zur Bekanntmachung geeigneten Verhandlungen der Königliche Preussischen Akademie der Wissenschaften zu Berlin, 13, p. 379; Last revision: Leidy 1878, Proceedings of the Academy of Natural Sciences of Philadelphia, 30, p. 172.

Synonyms: Difflugia ciliata Ehrenberg, 1848; Euglypha setigera Perty, 1852 (in part); Difflugia pilosa Ehrenberg, 1871; Difflugia Setigerella ciliata Ehrenberg, 1871; Difflugia Setigerella pilosa Ehrenberg, 1871.

Description: Shell colorless, transparent, oviform, compressed, elliptical in transverse section, with short siliceous spines slightly varying in size and distributed on lateral margin only (Fig. 102 A-E); spines attached to surface with small hemispherical nodules of organic cement, easily broken (Fig. 102 E, H); shell composed of oval overlapping shell-plates of about 4,5-6 x 3-4 μm, arranged in eleven to twelve longitudinal and eighteen to twenty transverse alternating rows (Fig. 102 A-D). Aperture oval, surrounded by ten to twelve roughly oval, denticulate apertural-plates, which are thickened at denticulate margin; each apertural plate with large median tooth, which does not exceed its outer margin, and two smaller lateral teeth on each side (Fig. 102 C, D, F, G). Cytoplasm does not fills entirely shell; one large ovular nucleus, with few nucleoli. Pseudopodia numerous, thin, long, fast moving.

Notes: The species has been recorded in both as nominal species and as infrasubspecific taxon E. ciliata f. glabra Wailes, 1915 (Rhodopes Mts., Rila Mts.).

Ecology: Frequent in mosses, freshwater habitats and Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Pateff 1924, Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2004, 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Euglypha ciliata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 64.8 64.8 4.40 0.80 6.79 56 74 30
Breadth 40.4 40.3 4.39 0.80 10.88 31 49 30
Diameter of aperture 14.1 14.1 2.27 0.41 16.14 10 18 30
Depth 25.1 25.5 1.87 0.56 7.45 22 28 11
Length of spines 8.7 9.0 1.91 0.36 21.95 5 12 28
Breadth/Length ratio 0.62 0.61 0.05 0.009 8.34 0.5 0.8 30
Aperture/Breadth ratio 0.35 0.35 0.04 0.007 11.37 0.3 0.4 30
Figure 102.

Scanning electron micrographs of Euglypha ciliata. (A-C) Broad lateral view of three specimens to show general shape, arrangement of shell plates and disposition of spines. (D) Narrow lateral view. (E) View of aboral region illustrating spines and their attachment to the shell surface. (F) Lateral view of apertural region. (G) Close up view of aperture. (H) Close up view of a single spine. (I) Detail of shell surface to show overlapping shell-plates.

Euglypha compressa Carter, 1864

Original description: Carter 1864, Annals and Magazine of Natural History, 13, no 73, p. 32, Pl. I, fig. 13.

Synonyms: Euglypha ampullacea Hertwig and Lesser, 1874; Euglypha ciliata Leidy, 1879 (in part); Euglypha α Vedovsky, 1882 (in part); ? Euglypha zonata Maggi, 1888.

Description: Shell large, colorless, transparent, broadly oviform, considerably compressed, elliptical in transverse section; with short siliceous spines slightly varying in size and distributed on lateral margin only (Fig. 103 A-F); spines attached to the surface with small hemispherical nodules of organic cement, easily broken (Fig. 103 F, H); shell composed of oval overlapping shell-plates of about 5-6 x 3,5-5 μm, arranged in fifteen to seventeen longitudinal and eighteen to twenty transverse alternating rows (Fig. 103 D-F). Aperture oval, surrounded by ten to fourteen roughly oval to triangular denticulate apertural-plates, which are thickened at denticulate margin; each apertural plate with large median tooth and three or four smaller lateral teeth on each side (Fig. 103 E-G). Cytoplasm fills about two-thirds of the shell; one large ovular nucleus, with few nucleoli (Fig. 103 A-B). Pseudopodia numerous, thin, radiating, sometimes branched, fast moving.

Notes: The species has been recorded in both as nominal species and as infrasubspecific taxon E. compressa f. glabra Wailes, 1915 (Rhodopes Mts.).

Ecology: Frequent in mosses, freshwater habitats and Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky et al. 2006); Rila Mts. (Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995, Bankov et al. 2018).

Euglypha compressa. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 72,6 73,5 5,15 0,96 7,09 63 83 29
Breadth 46,5 46,5 3,83 0,72 8,24 39 57 28
Diameter of aperture 16,6 16,8 2,21 0,41 13,31 12 20 29
Depth 24,6 25,5 3,40 1,13 13,82 17 29 9
Length of spines 7,7 6,0 4,05 0,84 52,59 4 18 23
Breadth/Length ratio 0,64 0,64 0,05 0,01 7,81 0,55 0,74 28
Aperture/Breadth ratio 0,36 0,36 0,04 0,01 11,11 0,29 0,43 28
Figure 103.

Light (A, B) and scanning electron (C-I) micrographs of Euglypha compressa. (A-C) View of many specimens to illustrate variability in shape and size of the shell. (D, E) Broad lateral view of two specimens to show general shape, arrangement of shell plates and disposition of spines. (F) Narrow lateral view. (G) Close up view of apertural region. (H) View of aboral region illustrating spines and their attachment to the shell surface. (I) Detail of shell surface to show overlapping shell-plates.

Euglypha cristata Leidy, 1874

Original description: Leidy 1874c, Proceedings of the Academy of Natural Sciences of Philadelphia, 26, p. 226.

Description: Shell colorless, transparent, elongated, with long, slightly-constricted neck, uncompressed and circular in transverse section; apex of the aboral region with a tuft of three to nine long, thin, flattened and tapering siliceous spines (Fig. 104 A-E, G, H); shell composed of oval to hexagonal, slightly overlapping shell-plates of about 8-9 x 5-6 μm, arranged in five to six longitudinal and eleven to thirteen transverse alternating rows (Fig. 104 C-E, I). Aperture circular, surrounded by five to six oval or hexagonal denticulate apertural plates, which are thickened at the denticulate margin; each apertural plate with large median tooth and three smaller lateral teeth on each side (Fig. 104 E, F). Cytoplasm fills almost whole shell; one small vesicular nucleus with central nucleolus. Pseudopodia usually one, rarely few, thin, long, directed straight ahead, fast moving (Fig. 104 A, B).

Notes: The species has been recorded in both as nominal species and as infrasubspecific taxon E. cristata var. major Wailes, 1911 (Vitosha Mts.).

Ecology: Common in Sphagnum.

Geographical distribution: Cosmopolitan.

Distribution in Sphagnum mosses in Bulgaria: Pirin Mts. (Bankov et al. 2018); Rhodopes Mts. (Golemansky 1968, Golemansky et al. 2006); Rila Mts. (Pateff 1924, Golemansky and Todorov 1993, Todorov and Golemansky 2000, Todorov 2005, Bankov et al. 2018); Stara Planina Mts. (Bankov et al. 2018); Vitosha Mts. (Pateff 1924, Golemansky 1965, Golemansky and Todorov 1985, 1990, Todorov 1993, Todorov and Golemansky 1995).

Euglypha cristata. Morphometric characterisation (measurements in μm)

Characters Mean M SD SE CV Min Max n
Length 50.1 52.2 6.84 1.17 13.65 31 59 34
Breadth 16.3 16.7 2.00 0.34 12.22 11 19 34
Diameter of aperture 8.3 8.6 1.39 0.24 16.77 5 11 34
Length of spines 9.8 9.7 3.05 0.65 31.20 5 16 22
Breadth/Length ratio 0.33 0.32 0.03 0.005 9.75 0.3 0.4 34
Aperture/Breadth ratio 0.51 0.51 0.07 0.01 14.40 0.4 0.7 34
Figure 104.

Light (A, B) and scanning electron (C-I) micrographs of Euglypha cristata. (A, B) View of several specimens to illustrate variability in shape and size of the shell. (C-E) Lateral view of three specimens to show symmetrical arrangement of shell plates and disposition of spines in centre of the aboral region. (F) View of apertural plates. (G-H) View of aboral region showing spines and their at