Family: Rhizosoleniaceae De Toni
Genus: Rhizosolenia (Ehrenberg) Brightwell
Scientific name: Rhizosolenia imbricata Brightwell
Rhizosolenia striata Greville
Hustedt, 1930: p. 582, Fig. 331; Allen and Cupp, 1935: p. 127, Fig.35; Crosby and Wood, 1958: p. 522, Pl. 39: 74 a; Hendey, 1964: p.149, Pl. III: 1; Hendey, 1970: p. 121; Simonsen, 1974: p. 29; Ricard,1987: p. 173, Figs. 216-218; Throndsen et al., 2007: p. 162.
Cells large, cylindrical, slightly flattened and furnished with depressed of flattened conical valves having a strongly oblique ventral margin.Valves furnished with a strong marginal spine which appears as a continuation of the dorsal side of the valve. Girdle composed of two lateral rows of intercalary scale-like markings. The segments have oblique ends, and their edges form regular rings around the cell. Intercalary scales coarsely striate, striae oblique, converging upon a line or hyaline break which runs up the middle of the girdle. Markings finely areolate. Diameter of valve up to 80 µm, length of cell up to 400 µm (Hendey, 1964).
Cells length 350-420 µm; diameter 45-58 µm.
Marine cosmopolitan species.
Sites of occurrence in RSA:
In Winter 2006 Cruise, this species was frequently observed at various sites (refer sites map),although never in large numbers; maximum abundance (9.9 102 cells/l) was associated with the Iranian coast in the Sea of Oman (St. 88). 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).