Valves are dorsiventral, with rounded to rostrate ends. Striae 12-14 in 10 μm, costae are 3-4 in 10 μm with 3-7 striae between costae. Dorsal margin is strongly convex and ventral margin is moderately concave. Raphe canal lies against the ventral margin at distal ends of the valve arching toward the dorsal margin in valve center. The central arch of the canal is approximately 3-6 μm above the ventral margin reaching less than half the distance to the dorsal margin.