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 medium in size, covered with spines, sinus open outward, 53-60 μm long, 50-53 μm wide, isthmus 20-26 μm wide; semicells nearly semicircular, basal corner rounded, apex smooth, apical view elliptical (Photomicrographs of the Fresh-water Algae, vol. 3, 1985).