Corythion dubium var. gigas Thomas, 1953
Diagnosis: shell ovoid, composed of oval shell-plates, irregularly arranged, very small and usually overlapping each other; aperture sub-terminal, oval and invaginated.
Dimensions: Length 76-90 µm; breadth 34-42 µm; mouth 14-18 µm.
Ecology: Sphagnum and mosses.
Remarks: This variety strongly resembles Trinema enchelys, but differs in the shape of the plate scales.
M. ovalistoma – after Bartos, 1963 Metaheleopera Bartos, 1963 Diagnosis: Shell clearly narrowing towards the pseudostome, which can be seen even more clearly on the narrower sides
M. radixicola – after Chardez, 1974 Matsakision radixicola Chardez, 1974 Diagnosis: Shell ovoid, slightly compressed, transparent; pseudostome oval, truncated perpendicularly, with a slight neck. Shell
M. cassagnaui – after Bonnet, 1967 Matsakision cassagnaui Bonnet, 1967 Diagnosis: Shell hyaline, elongated ovoid, very little compressed, truncated perpendicularly or very slightly obliquely in
Matsakision – after Bonnet, 1967 Matsakision Bonnet, 1967 Diagnosis: Shell hyaline, elongated ovoid, very little compressed, truncated perpendicularly or very slightly obliquely in the region
Arcella marginata, after Deflandre, 1929 Arcella marginata Daday, 1905 Diagnosis: Shell roughly hemispherical, rather overhanging, with a flattened, smooth edge. In dorsal view showing a
Arcella lobostoma, after Deflandre, 1929 Arcella lobostoma Deflandre, 1929 Diagnosis: Shell hemispherical. In ventral view, irregular circular outline, often a little elliptical; pseudostome irregularly lobed: