Cells solitary, generally free-floating, or in tough mucous film adhering to a substratum. A girdle view shows elliptical with truncated flattened ends. Frustules asymmetric, shaped like a third of an orange. Valves not parallel with each other, but with surfaces in planes at an angle one with another. Valves curved or sublunate, and in the complete frustule, the ventral margins lie parallel and close to each other, with the raphes of the two valves in the same focal plane, while the dorsal margins are separated by a very deep development of the girdle. Raphe usually eccentric, lying closer to the ventral margin; valve surface striate, usually punctate; ventral side narrower, and often without structure or with less structure than on the arcuate dorsal side; girdle usually complex, composed of numerous bands that may or may not bear puncta. Chromatophores: very variable, and may be from one to four irregularly shaped plates, or as numerous granules (Hendey, 1964).
Witkowski et al., 2000: p. 142, Pl. 167: 17-19.
Frustules in girdle view rectangular-elliptic, usually with slightly convex margins, 30-60 µm long; 13-28 µm broad. Valves semilanceolate; ventral margins almost straight with not produced, acutely rounded apices, 3.5-7 µm broad. Raphe biarcuate; external central endings bent toward dorsal side; axial area very narrow; central area absent or very small. Transapical 0striae on the dorsal and ventral side in the middle radiate, toward apices convergent, 20-25 in 10 µm (Witkowski et al., 2000).
Cells length 55 µm; width 12 µm.
Sites of occurrence in RSA:
In Winter 2006 Cruise, it was present in small numbers at three stations (refer sites map).