Genus: Trichome without mucous sheath; straight, long, consisting of numerous cells (Illustrations of The Japanese Fresh-water Algae, 1977). Species: Trichome nearly straight, slightly tapered toward both ends, without constriction at septum, 4-6 μm wide; cell body 2.5-4 μm long, granules present along septum; pseudovacuoles also present; terminal cells variable in shape, sometimes form conical-shaped calyptra, or rounded (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640

Oscillatoria agardhii Gomont ? (left), cell body (left) 9 μm long, 4 μm wide, cell body (right) 3-6 μm long, 8 μm wide, x 640, drainage ditch near Tanohara Natural Park, Ontake highland, Otaki town, Nagano Pref., Japan, June 26, 2005 by Y. Tsukii