Species [ var. bioculatum ]: Cell body small in size (length = width), 15-(18-21) μm long, 15-(17-20)-21 μm wide, isthmus (5-5.5)-6.7 μm wide; semicells elongated ellipsoid, apex flattened, side view nearly circular, apical view elongated ellptical; cell wall smooth, transparent [ var. depressum ]: Cell body nearly rectangular, each corner rounded, 14.5-(18)-20 μm long, 17-18-(22) μm wide, isthmus 7 μm wide; semicells elongated ellipsoid (Illustrations of The Japanese Fresh-water Algae, 1977).

Similar species -->> C. depressum; C. contractum;

31 μm 63 μm 94 μm; x 640