Genus: Cell body long cylindroid; a slight constriction at center; cross section of the semicells spherical, slightly swell at the center but without a folded structure as Docidium; slightly tapered toward both ends, which are truncated and smooth or surrounded by granules or various small structures; laterally straight or wavy, with spiny projections in some species; 2-10 ribbon-like chloroplasts in each semicell; with many pyrenoids; a vacuole containing active granules at both ends same as in Closterium; cell wall mostly dotted, but with spines or other patterns in some species (Illustrations of The Japanese Fresh-water Algae, 1977). Species:

31 μm 63 μm 94 μm; x 640

Images of collecting locality: No.4, Iroha-numa (marsh/bog), Zao mountain, Kaminoyama city & Yamagata city, Yamagata Pref., Japan, July 13, 2008 by Y. Tsukii