Cryptodifflugia oviformis Penard, 1902
Diagnosis: shell ovoid, not of slightly compressed; surface smooth, sometimes covered with some xenosomes; young shells colorless, older shells yellow to deep brown; aperture with a thick collar.
Dimensions: L 14-35 µm, B 8-20 µm.
Ecology: fresh water, in different water types; usually on waterplants and in Sphagnum. Very common, sometimes abundant.
Remarks: Shell wall is comprised of a thin outer organic layer and a much thicker inner, non-crystalline calcareous layer (Hedley et al. (1977))