Species: Cell body 58-75 μm long, 26.5-31 μm wide, L/W=2-2.5, isthmus 20-29 μm wide; semicells broad ellipsoidal or ovoidal, apex broad circular or narrowly flattened; cell wall finely dotted; band-form chloroplasts aligned along inner cellwall (Illustrations of The Japanese Fresh-water Algae, 1977).

Similar species -->> C. oblongum; C. cucurbita; C. cucurbitinum; C. diplosporum; C. globosum;

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.12, a marsh pond at Sensho-ga-hara, near Akita-komagadake (mountain), Shizukuishi town, Iwate Pref., Japan, August 6, 2007 by Y. Tsukii