Family: Trichome (filamentous structure) with heterocysts; with equal diameter throughout hole length; no branching; heterocysts intervening or at base. Genus: Mucous sheath, nearly invisible; heterocysts intervening; filments solitary or agglutinate within a gelatinous matrix (Illustrations of The Japanese Fresh-water Algae, 1977).

31 μm 63 μm 94 μm; x 640