- Rotational symmetry of cell face outline is 360 degrees with one end broader than other
In this section
Valves identical, each possessing a raphe (genus is biraphid). Asymmetric in valve view, with one pointed end; the other bluntly rounded to pointed, but with the widest part of the valve often offset from the central area. Wedge shaped in girdle view. Attached to the bed by long mucilaginous stalks. Can form pale-yellowish blooms on unshaded stony streambeds, but considerably less abundantly than Didymosphenia.