Family: Chaetocerotaceae Ralfs in Pritchard
Genus: Bacteriastrum Shadbolt
Scientific name: Bacteriastrum hyalinum Lauder
Pavillard, 1925: p. 37, Fig. 58; Hustedt, 1930: p. 614, Fig. 354; Allen and Cupp, 1935: p. 131, Fig. 47; Cupp, 1943: p. 97, Fig. 56 A; Hendey, 1964: p. 139, Pl. VI: 1; Ricard, 1987: p. 217, Fig. 537; Throndsen et al., 2007: p. 163.
Cells cylindrical, 14-28 µm in diameter. Pervalvar axis often shorter than diameter. Chains long, straight or slightly curved. Apertures narrow, but distinct. Inner setae 12-25 on each valve, with short basal part.Bifurcations in pervalvar axis (parallel to chain axis) giving cells a hairy appearance. Forked parts are slightly curved and usually weakly twisted.Terminal setae differ little from those of B. delicatulum, umbrella-shaped, stronger than inner setae, and with spirally arranged tiny spines as in previous species. Chromatophores small and numerous. Resting spores in pairs in adjacent cells, one in each cell. With high arched valves, the primary valve is slightly contracted above the base, with fine spines when fully formed, smooth in process of formation. Secondary valve is similarly rounded and smooth (Cupp, 1943).
Cells diameter 22-26 µm.
Sites of occurrence in RSA:
In Winter 2006 Cruise, this species was frequently observed at various sites (refer sites map),often in large numbers; maximum abundance (4.7*10^4 cells/l) was associated with the Strait of Hormuz (St. 16a). It has been previously reported from Kuwaiti waters of the inner RSA (Al-Yamani et al., 2004; Al-Kandari et al., 2009).