Genus: Cell body crescent in shape (long, curved, tapered at both ends); cross section rounded;
cell wall smooth or with longitudinal lines, bands on the cell wall in some species;
chloroplast laminae ridged and radially arranged, which makes cross section star-shaped;
pyrenoids aligned or scattered (Illustrations of The Japanese Fresh-water Algae, 1977).
Subgenus [Euclosterium]: Cell body curved.
Species:
250-(396-576)-790 μm long, 25-(33-84) μm wide;
cell body large, slightly curved; both termini tapered; pyrenoids 7-15 in each semicell
(Illustrations of The Japanese Fresh-water Algae, 1977).
Cell body slightly curved, gradually attenuated toward the truncated ends, which somewhat recurved
due to the covexity of the inner margin near the ends; inner margin straight or slightly concave,
outer margin convex, 300-500 μm long, 32-50 μm wide, L/W=9-14;
cell wall smooth and colorless or sometimes delicately striated and yellowish-brown in color;
chloroplasts with ridges containing 7-11 pyrenoids in central row
(Photomicrographs of the Freshwater Algae, vol. 1, 1984).