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).

50 μm 100 μm 150 μm; x 400: 31 μm 63 μm 94 μm; x 640

Scenedesmus denticulatus Lagerheim var. fenestratus, cell body μm long, μm diam., short spines μm long, L/W= , S/L= , x 400, x 640, Binnuma River, Omiya City, Saitama Pref., September 2000, by Y. Tsukii
50 μm 100 μm 150 μm; x 400: 31 μm 63 μm 94 μm; x 640

* Scenedesmus denticulatus Lagerheim 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).

Scenedesmus denticulatus var. linearis Hansgirg: Cells longer than var. denticulatus; all cells have dented projections at both termini, cell body 7-16 μm long, 2.5-4.5 μm diam. (Illustrations of The Japanese Fresh-water Algae, 1977).

Scenedesmus denticulatus var. linearis f. granulatus Hortobagyi: Similar to var. linearis but cell wall covered with small granules linerally arranged; cell body 10-15 μm long, 2.7-4.4 μm diam. (Illustrations of The Japanese Fresh-water Algae, 1977).

Scenedesmus denticulatus var. fenestratus Uherkovich: Colonies of 4-8 cells loosely attached; cell body 8-10(-15) μm long, 4.5-6(-8) μm diam. (Illustrations of The Japanese Fresh-water Algae, 1977).