Genus: Filament without branching; cell body cylindrical; two chloroplasts star-shaped;
tubes formed (or cell body fused) at conjugation; zygospore spherical or broad ellipsoidal formed within female gametangium
(Guide book to the "Photomicrographs of the Freshwater Algae", 1998).
Species: Cell body 25-120 μm long, 30-36 μm wide; conjugation scalariform; zygotes formed within the tube, spherical or broad ellipsoidal, 40-54 μm long, 35-44 μm wide; surface layer yellowish brown, covered with small pores (2-3 μm φ) (Illustrations of The Japanese Fresh-water Algae, 1977).
Zygnema excompressum Transeau: vegetative cells 32-80 μm long, 23-26 μm diam., 2 chloroplasts in each cell