Pavillard, 1925: p. 57, Fig. 101; Hustedt, 1930: p. 876, Fig. 519; Allen and Cupp, 1935: p.149, Fig. 88; Cupp, 1943: p. 169, Fig. 119; Crosby and Wood, 1958: p. 509, Pl. 36: 24;Hendey, 1970: p. 119; Simonsen, 1974: p. 33; Ricard, 1987: p. 187, Figs. 326-329.
Cells broadly elliptical in valve view. Chains straight or curved, more or less long. Pervalvar axis more or less elongated. Apical axis 15-36 µm long. Valves with slightly convex surface of elliptical outline. Valve mantle high, no groove at base. Processes on valves thin, but strong, with a strong claw on the ends. Cell wall more strongly siliceous than in H. hauckii, areolated-punctated.
Areolae in radial, on the mantle surface pervalvar, rows of characteristic excentric arrangement, in that the center of the areolation does not coincide with the center of the valve, but lies on one of the mantle surfaces. Areolae in the center of the valve 7-9 in 10 µm, on the base of the mantle 11-13 in 10 µm. Intercalary bands visible with special preparation. Very fine punctation present on bands in rows, 28-29 rows in 10 µm (Cupp, 1943).
Cells length 38-55 µm; width 17-21 µm.
Neritic, south temperate or subtropical species.
Sites of occurrence in RSA:
In Winter 2006 Cruise, this species occurred occasionally at various sites (refer sites map),usually in small numbers, however, it was quite abundant at some localities; maximum abundance (8.2 103 cells/l) was associated with Kuwaiti waters in the northwestern part of the inner RSA (St. 1, 14). It has been previously reported from the inner RSA (Simonsen, 1974) and from Kuwaiti shore (Hendey, 1970) and coastal waters (Al-Yamani et al., 2004;Al-Kandari et al., 2009).