Genus: Unicellular; variable in shape; a constriction at the center of the cell body; mostly longer than wide; flattened; each semicell hemispherical, spherical, ellipsoidal, rectangular, pyramidal or kidney-shaped; no apical indentation (Illustrations of The Japanese Fresh-water Algae, 1977).
Species: cell body 35 μm long, 24 μm wide, constriction 12.6 μm wide, cell surface with laterally 6 wavy up-and-down (Illustrations of The Japanese Fresh-water Algae, 1977).