Genus: Cingulum (horizontal groove) located at the center of the body
(Illustrations of The Japanese Fresh-water Algae, 1977).
Cingulum more or less median; sulcus straight (Illrustrated Guide, 1985).
Gymnodinium aeruginosum Stein 1939 ?,
cell body 29 μm long, 20 μm wide,
x 640, Imori pond, Myoko-kogen (Myoko highland), Myoko village, Niigata Pref., Japan, November 7, 2004 by Y. Tsukii
94 μm; x 640