Genus: Body more or less ovo-cylindrical; rigid with spirally striated pellicle; often with a short posterior spinous projection; stigma sometimes present; discoidal chromatophores (chloroplasts) numerous and marginal; paramylum bodies usually large and ring-shaped, laterally disposed; without pyrenoids; fresh water (Kudo, 1966).

50 μm 100 μm 150 μm; x 400 : 31 μm 63 μm 94 μm; x 640