Species: Cell body 180-(210-493)-540 μm long, (24-45)-52 μm wide (cf. C. intermedium < 25 μm), L/W = 8-12, slightly curved, tapered at both ends, not swelled in the middle (cf. C. rostratum), both ends broadly truncated with slanting edges; cell wall brown in color and striated, 5-10 striae in 10 μm; chloroplasts with with 5-9 pyrenoids in each semicells (Illustrations of the japanese fresh-water algae, 1977). Both ends are obliquely truncate-convex; striae about 20 across the cell; chloroplasts with 5-6 pyrenoids in each semicells; 210-490 μm long, 24-45 μm wide (Phtomicrographs of the fresh-water algae, 1984).

50 μm 100 μm 150 μm; x 400 : 31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.2, standing water, Nakayukawa-sen (a forestry road along Omatazawa), Nishiwaga town, Iwate Pref., Japan, July 28, 2007 by Y. Tsukii