Family: With two unequal flagella (heterokonta); no pellicle and plastic (Kudo, 1966).
Genus: Solitary or colonial; body surface delicate; one to two chloroplasts; usually with a stigma; fresh water (Kudo, 1966). One to several chloroplasts; pyrenoid and/or eyespot (stigma) in some; cells naked, globular, ellipsoidal or pyriform (Illustrated Guide, 1985).

O. variabilis 16 clips Japan, 1998