Cells shortly cylindrical; united to form chains. Valves circular. Valve surface with faint radial lines merging into a wide, downwards sloping valve margin, and valve mantle that is strongly loculate and ornamented with a coarse network of sub-hexagonal cellulation. Chromatophores usually numerous small rounded bodies (Hendey, 1964)
Melosira sulcata (Ehrenberg) Kützing;Gaillonella sulcata Ehrenberg
Pavillard, 1925: p. 4, Fig. 1; Hustedt, 1930: p.276, Fig. 118; Allen and Cupp, 1935: p. 112,Fig. 1; Cupp, 1943: p. 40, Fig. 2 (as Melosirasulcata); Crosby and Wood, 1958: p. 489, Pl.31: 2 (as Melosira sulcata); Hendey, 1964: p.73, Pl. XXIII: 5; Hendey, 1970: p. 109; Simonsen, 1974: p. 8; Ricard, 1987: p. 167, Fig. 174-182; Witkowski et al., 2000: p. 37, Pl. 8: 10, 11; Throndsen et al., 2007: p. 145.
Girdle view: dense chains. Cell wall, coarsely silicified. Cells wider than high. Valve face flat; several small disc-shaped chloroplasts. Valve view: end valve of chains without spines and elevations. Pervalvar axis 3-45 µm; diameter 8-130 µm (Throndsen et al., 2007).
Cells length 8-12 µm; diameter 15-22 µm.
Species is common in coastal plankton.
Sites of occurrence in RSA:
In Winter 2006 Cruise, this species occurred at different sites (refer sites map) in small numbers;maximum abundance (5.2*10^2cells/l) was associated with the central part of the inner RSA (St.43). It has been previously reported from the northern part of the inner RSA (Simonsen, 1974)and from Kuwaiti shore (Hendey, 1970) and coastal waters (Al-Yamani et al., 2004; Al-Kandari
et al., 2009).