Valves are lanceolate with subrostrate ends. Striae are slightly radiate throughout the valve, parallel or slightly convergent at the apices, 27-31 in 10 μm. The raphe is absent on one of the valves. The raphe valve has a narrowly lanceolate axial area and round central area expanded to the valve margin on one or both sides. The axial area of the rapheless valve is lanceolate.