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: Cell body fusiform, straight or slightly curved, both ends drawn out, 28-50 μm long, 4-8 μm wide; cells arranged alternately contacting with their apices and median portion of adjacent cells in a linear series; cell wall smooth, without teeth or spines (Photomicrographs of the Freshwater Algae, vol. 15, 1995).

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