Family: Unicells or colonies of non-fixed number of cells; cell body variable in shape; one or more chloroplasts variable in shape; asexual reproduction by autospore or autocoenobium (Illustrations of The Japanese Fresh-water Algae, 1977).
Genus: Unicellular; planktonic; cell body elongated spindle-shaped or crescent in shape, laterally unsymmetrical, both ends attenuated; autospores attached each other at their one ends arranging radially; a single chloroplast plate-like, with a pyrenoid (Guide book to the "Photomicrographs of the Freshwater Algae", 1998).