Family: Colonial, usually with a gelatinous coat; 4 daughter cells are connected with filaments derived from their maternal cell wall; cell body spherical, elliptical or heart-shaped; a single chloroplast plate-like or cup-shaped containing a pyrenoid; asexual reproduction by autospore, sexual reproduction by fertilization of egg and sperm.
Genus: Cells are equal in size (Illustrations of The Japanese Fresh-water Algae, 1977). Planktonic; colony within a gelatinous sheath; cell body spherical, elliptical or pear-shaped; 4 daughter cells attached to a filament dichotomously radiating from the center of the colony; a single chloroplast cup-shaped, with a pyrenoid.