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 surrounded by mucilage; cell body oblong cylindrical with rounded ends,
6.4-17.5 μm long, 1.7-6.6 μm wide;
cells arranged in a linear series contacting with about 80% of lateral walls, outer cells slightly convex,
with short spines on cell pole in two lateral rows,
inner cells on one side with a longitudinal row of short spines; cell wall smooth
(Photomicrographs of the Freshwater Algae, vol. 19, 1997).
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