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 [ var. reniforme ]: Cell body medium in size, slightly longer than width, (47-56)-57 μm long, (32-34.4)-38-40 μm wide, isthmus 15-(17)-20 μm wide; semicells reniform, side view circular, apical view elliptical; cell wall covered with granules (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.3, Omine-numa (pond/marsh), Minakami town (formerly Tsukiyono town), Gunma Pref., Japan, October 12, 2008 by Y. Tsukii