Species :
Cell body small in size (length = width), 12-16.7 μm long, 9.5-15.5 μm wide,
isthmus 4.3-5.6 μm wide; semicells ellipsoidal, apex broadly convex or nearly flat
(Illustrations of The Japanese Fresh-water Algae, 1977).
Similar species -->>C. depressum;
C. contractum;
Cosmarium inconspicuum Archer,
cell body 12.5 μm long, 10 μm wide, isthmus 3 μm wide,
x 640, Omine-numa (pond/marsh), Tsukiyono town, Gunma Pref., Japan, September 2003 by Y. Tsukii
31 μm
63 μm
94 μm; x 640