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: Coloies of 4, 8 cells, attached adjacent cells at the center, arranging linearly; cell body spindle-shaped, 12-28 μm long, 5-8 μm wide; outer cells with long spiny projections 5-28 μm long; inner cells sometimes with a short spines (Illustrations of The Japanese Fresh-water Algae, 1977). Cells arranging lineary but not on a flat plane, outer cells attached inner cells slightly frontal side, thus forming a plane curve.

Similar species -->> S. carinatus; S. protuberans; S. quadricauda; S. circumfusus;

31 μm 63 μm 94 μm; x 640