Guide to Rhoicosphenia stoermeri

Valves are linear to narrowly clavate, with acute apices. The proximal raphe ends are broadly spaced from one another and positioned within a panduriform central area. Valves range from 80 to 25 µm in length and 6-9 µm in width. Areolae are distinctly lineate and number 11–13 in 10 μm.