Family: Unicells or colonies of non-fixed number of cells; cell body variable in shape;
one or more chloroplasts variable in shape; a sexual reproduction by autospore
(Illustrations of The Japanese Fresh-water Algae, 1977).
Genus: Colonies of 4, 8 or 16 cells; planktonic; body crescent in shape; tapered at both ends;
cells attached to each other at dorsal surface; a chloroplast curved plate-like, with a
pyrenoid
(Guide book to the "Photomicrographs of the Freshwater Algae", 1998).