Encyonema triangulum

Valves are elliptic-lanceolate and moderately asymmetric to the apical axis, with smoothly convex dorsal and ventral margins. The apices are and acute and apiculate. The axial area is variable in width, 3-6 times wider than the raphe. The central area is only slightly wider than the axial area. The raphe is lateral and arched, becoming concave toward the dorsal side. Proximal raphe ends are slightly expanded and deflected dorsally; distal raphe ends are recurved ventrally. Striae are slightly radiate, becoming parallel and then convergent at the apices, especially on the ventral side. The central one or two striae on the dorsal side are often slightly longer than adjacent striae. Areolae are very coarse and number 8-10 in 10 µm.