Genus: Filamentous algae, axis-branch differentiation incomplete; terminal cells tapered to form spiny projections;
branches do not form in tuft
(Illustrations of The Japanese Fresh-water Algae, 1977).
Species: Branching not so frequent; secondary branching rare; branching axial cells shorter compared to non-branching cells; axial cells up to 8-12-(15) μm in diam., L/W=2-4; constriction present at cell junction (Illustration of the Japanese fresh-water algae, 1977).
Images of collecting locality:
a drainage ditch near South Crossing at Yase-Ohashi (bridge), Ikebe, Kawagoe city, Saitama Pref., Japan, February 25, 2007 by Y. Tsukii