Family: Chaetocerotaceae Ralfs in Pritchard
Genus: Chaetoceros Ehrenberg
Scientific name: Chaetoceros curvisetus Cleve
Pavillard, 1925: p. 51, Fig. 82; Hustedt, 1930: p. 739, Fig. 426;Cupp, 1943: p. 138, Fig. 93; Hendey, 1964: p. 133, Pl. XVII: 6;
Simonsen, 1974: p. 30; Priddle and Fryxell, 1985: p. 44-45;Ricard, 1987: p. 207, 215, Figs. 475, 476, 526, 527; Throndsen
et al., 2007: p. 172.
Chains spirally curved, without distinct terminal cells, 7-30 µm wide. Cells four-cornered in broad girdle view, adjacent cells connected by conspicuous corners. Valve mantle usually low,higher at corners of apical axis, very small notch at junction with girdle band. Apertures rhombic, oval, or circular. Setae arising from corners of cells, all bent toward same side of chain - toward outside of curved axis of spiral. Chromatophores one per cell with large central pyrenoid. Resting spores central, smooth, surrounded by thickened girdle of mother cell, more or less rounded valves, without spines; on margin of primary valve, a row of delicate puncta (Cupp, 1943).
Apical axis 9-11 µm; pervalvar axis 10-13 µm.
Neritic, south temperate species.
Sites of occurrence in RSA:
In Winter 2006 Cruise, this species was frequently observed at various sites (refer sites map),often in very large numbers. It was recorded as bloom-forming at some localities; blooms with cell concentration of more than 10^6 cells/l were associated with the Sea of Oman (Stations 88, 25a, and 92). It has been previously reported from the Indian Ocean (Simonsen, 1974) and from Kuwaiti waters of the inner RSA (Al-Yamani et al., 2004; Al-Kandari et al., 2009).