Genus: Colonies of 4 (or 2, 8, 16) cells attached side by side, arranged linearly or zigzag; cell body elliptical or spindle or crescent in shape; terminal cells with spiny projections in many species; cell wall usually smooth, but in some species granulated or dented or ridged (Illustrations of The Japanese Fresh-water Algae, 1977). Species [ var. denticulatus ]: Colonies of 4-8 cells arranged in a slightly zigzag pattern or straight; cells at both ends have 2-3 dented projections at both termini, inner cells have such projections at only one terminus; cell body 10-15 μm long, 5-10 μm diam. (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.2, Kejo-numa, Furukawa-Ono, Osaki city (formerly Furukawa city), Miyagi Pref., Japan, October 29, 2006 by Y. Tsukii