Genus: Unicellular; variable in shape; a constriction at the center of the cell body; mostly longer than wide; flattened; each semicell hemispherical, spherical, ellipsoidal, rectangular, pyramidal or kidney-shaped; no apical indentation (Illustrations of The Japanese Fresh-water Algae, 1977).
Species: Cell body small, (25-36.4)-42 μm long, (22.6-28)-36 μm wide, isthmus (7-9.7)-12 μm wide; (Illustrations of the Japanese fresh-water algae, 1977).
C. sexangulare
var. sexangulare
41 x 31 μm
Yasuji-kawa
Sawara
Chiba, 2004
C. sexangulare
var. sexangulare
38 x 29 μm
Univ. A.V.M.
Obihiro
Hokkaido, 2005
