Hemidiscus hardmanianus (Greville) Mann
Allen and Cupp, 1935: p. 151, Fig. 91 (as Hemidiscus hardmanianus); Simonsen, 1974: p. 19; Hasle and Syvertsen, 1997: p.
112, Pl. 18.
Valves semicircular; valve face approximately plane. Central area of valve is hyaline. Radial areolation with incomplete striae, inserted from the margin. Distinct hyaline lines, associated with marginal processes, two processes larger than the others. The ventral line of small labiate processes (those along the straight valve margin) is ca 10 areolae away from the margin. Length 303-534 µm, width 162-270 µm, 12-14 areolae in 10 µm (Hasle and Syvertsen, 1997).
Cells length 420-450 µm; width 190-230 µm.
Sites of occurrence in RSA:
In Winter 2006 Cruise, this species occurred at few sites (refer sites map) in very small numbers. It has been previously reported from the inner RSA (Simonsen, 1974) and from Kuwaiti waters (Al-Kandari et al., 2009).