Rhopalodia Gibberula Guide
Credit: Elaine Jordan
  1. Valves lunate
  2. Striae 2-6 between costae
  3. Apices slightly bent ventrally ,or protracted and acutely rounded

Valves are lunate, with strongly convex dorsal margins that are often slightly notched in the middle.The ventral margin is slightly concave to straight. In girdle view, frustules are broadly lanceolate to elliptical. Apices are slightly bent ventrally, or protracted and acutely rounded. The raphe is located on dorsal margin and is difficult to distinguish. Transapical costae may be slightly radiate.