Genus: Variable in shape and in size; mostly longer than wide; strong constriction at center; semicell pyramid-shaped, apically flattened with indentation (or notch, some species lack this notch); laterally straight or wavy or indented; one chloroplast in each semicell; one pyrenoid for each chloroplast (Illustrations of The Japanese Fresh-water Algae, 1977).

E. gemmatum x 640	E. crameri x 640	E. elegans x 640	E. turnerii x 640
E. sublobatum x 640	E. sublobatum x 640