Scale Bar = 10 micrometers.

This genus can be distinguished from Gomphonema by the curvature of the valves. It is frequently seen in girdle view and is strongly arcuate. One valve displays a full raphe and the opposite valve displays a rudimentary raphe that only extends ~1/5th of the way up the valve from the footpole. Pseudoseptae are present. This species has rounded headpoles and is arcuate along the length of the valve unlike R. californica.