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: Colonies enclosed by a gelatinous envelope, always curved; cell body reniform, sometimes elliptical, with broadly rounded ends, young cells 6.5-7 μm long, 3 μm wide, mature cells up to 16.5 μm long, 9 μm wide; cells arranged in cruciate series (when 2 cells), or in double series, sometimes irregular (when 8 cells) ; cell wall smooth, without teeth, spines or granulations (Photomicrographs of the Freshwater Algae, vol. 3, 1985). Similar species -- > > S. ecornis

31 μm 63 μm 94 μm; x 640