Genus: Free-swimming; rigid oval; ventral surface convex; dorsal surface with a longitudinal groove;
flagella anterior; one long, directed anteriorly; the other shorter and trailing; fresh water
Species: Cell body ovoid, 24-40 μm long, 10-25 μm wide, dorsally with a deep, median longitudinal groove (Larsen and Patterson, J. Natural History, vol. 24, 801-937, 1990).