 
 
|  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 (var. subnudum): Cell body (42)-51 μm long, (33.6)-41 μm wide, isthmus 11-(14.5) μm wide, apex slightly depressed; (Illustrations of The Japanese Fresh-water Algae, 1977). 
 
 | 
 50 μm
 50 μm
 100 μm
 100 μm
 150 μm; x 400 :
 150 μm; x 400 : 
 31 μm
 31 μm
 63 μm
 63 μm
 94 μm; x 640
 94 μm; x 640
 
 
Cosmarium sportella Brébisson var. subnudum: Cell body (42)-51 μm long, (33.6)-41 μm wide, isthmus 11-(14.5) μm wide, apex slightly depressed; (Illustrations of The Japanese Fresh-water Algae, 1977).