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 small, 18-(19.6-29.4) μm long, 18-(19.6-25) μm wide, isthmus 4.5-(5.6-7) μm wide; semicells somewhat reniform, apex convex, apical view elongated elliptical, with small projections at both sides (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640