Diagnosis_Genus : Stein, 1883
Body_length : 30-150 µm
Medium-sized to large (30-150 µm) flagellate with elaborate to bizarre wings and lists. Cell body divided by large cingular lists into a small to very much reduced epicone, nearly flat to rather strongly vaulted, and a larger ovoid to naviculoid hypocone as seen from the lateral side. Only in very few species the hypocone forms a conspicuous antapical horn. Many species are laterally very much compressed. As the epicone is small, the circular cingulum is always displaced to the anterior part of the cell. The hypothecal cingular lists are bent to the longitudinal axis extending to the apex, forming a wide cylinder. In some species the dorsal and ventral width is equal or subequal, in others it may be much higher dorsally than ventrally. The epithecal cingular lists also are bent to the longitudinal axis, closed and funnel-shaped resulting in a large chamber between the hypothecal and epithecal cingular lists.