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:
Cosmarium sp.,
outline shape similar to C. depressum
but cell surface granulated not smooth,
cell body 23 μm long, 23 μm wide, L/W=1.0, isthmus 7 μm wide,
x 640, a water reservoir (pond) near Yamaguchi university, Yamaguchi city, Yamaguchi Pref., November 21, 2004, by Y. Tsukii
31 μm
63 μm
94 μm; x 640
Cosmarium ozense Hirano:
Cell body 17-18 μm long, 18-18.5 μm wide, isthmus 7 μm wide;
semicells rectangular (Illustrations of the Fresh-water Algae, 1977).