Species: Cell body elongated spindle-shaped, 220-(240-312) μm long, (10-11)-14 μm wide, L/W=20-26 (cf. C. strigosum,150-410 μ L/W=10-18); cell wall transparent, smooth; chloroplasts with 3-6 pyrenoids (Illustrations of The Japanese Fresh-water Algae, 1977). Cell body (110-)150-250(-310) μm long, (6-)8-12(-14) μm wide; L/W=(12-)15-30(-35), (Coesel & Meesters 2007).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.4, a marsh pond at Sensho-ga-hara, near Akita-komagadake (mountain), Shizukuishi town, Iwate Pref., Japan, August 6, 2007 by Y. Tsukii