Valves with a highly arched dorsal margin. The ventral margin is straight to concave, with a tumid area in the center. The axial area is narrow and slightly enlarged at the center to form an ovoid to irregular central area. A single stigma is positioned in the center of the central area. Areolae around the central area are elongated, especially on the ventral side. The apicies possess a distinct apical pore fields and the distal raphe ends are deflected around them.