Family: Colonies of a fixed number of cells (4, 8, 16, 32, or more) arranged 2- or 3-dimensionally; cells spherical, ellipsoidal, polygonal, etc. in shape; chloroplasts 1 or several, plate-like in shape, with 1 pyrenoid; asexual reproduction by autocoenobium (Illustrations of The Japanese Fresh-water Algae, 1977).
Genus: Colony of two cells, planktonic; cell body ellipsoidal, both ends rounded; two cells attached side by side; cell wall smooth, covered thin spiny projections; each projection swell at the base; two chloroplasts plate-like in shape, with a pyrenoid (Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
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cell 8 x 14 μm