Genus: Filament without branching; cell body cylindrical; each cell wall consists of two parts with "H" structure overlapping at the midregion; chloroplasts many, disc-shaped, without pyrenoids (Guide book to the "Photomicrographs of the Freshwater Algae", 1998). Filament 10-12-(-15) μm wide (Süßwasserflora von Mitteleuropa 3, Xanthophyceae 1, 1978). Filament 8-12 μm wide; many chloroplasts in each cell (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Tribonema subtilissimum Pascher: Filament 2-3 μm wide; cell body 4-8 times longer than its width; many disc-shaped chloroplasts (Süßwasserflora von Mitteleuropa 3, Xanthophyceae 1, 1978).