Genus: Colonies of 4-32 cells; cell body long crescent or spindle in shape, tapered at both ends;
cells attached with each other at the center of the body, paralleled or radially arranged;
no gelatinous sheath; a chloroplast; no pyrenoids; planktonic
(Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
* Ankistrodesmus falcatus (Corda) Ralfs: 25-30 μm long, 2-3 μm wide (Illustrations of The Japanese Fresh-water Algae, 1977).
Ankistrodesmus gracilis (Reinsch) Korshikov (Syn: Selenastrum gracile Reinsch): A colony of 8-32 cells, cells crescent in shape, 10-15 μm long, 3-5 μm wide, a single flattened chloroplast and a pyrenoid (Illustrations of The Japanese Fresh-water Algae, 1977).