Genus: Generally ovoid; asymmetrical; plastic or rigid; a slit-like ventral furrow; flagella at anterior end; cytopharynx long; contractile vacuole anterior; nucleus posterior (Kudo, 1966). Lightly striated; trailing flagellum longer than anterior one (How to know the protozoa, 1979).
Species: 25-40 μm long, 16-22 μm wide; rigid, oval; somewhat flattened; pellicle slightly striated (Kudo, 1966). Rigid; faintly spirally striated; fresh water (How to know the protozoa, 1979).