Pavillard, 1925: p. 53, Fig. 89; Hustedt, 1930: p. 773, Fig. 451; Allen and Cupp, 1935: p.142, Fig. 74; Cupp, 1943: p. 145, Fig. 103; Crosby and Wood, 1958: p. 511, Pl. 36: 28;Hendey, 1964: p. 107, Pl. VII: 1; Simonsen, 1974: p. 34; Ricard, 1987: p. 189, Figs. 342,343; Throndsen et al., 2007: p. 178.
Cells flattened, elliptical-linear in valve view, united in chains by two blunt processes. Chains spirally curved, with relatively narrow lanceolate or elliptical apertures. Apertures variable in size and shape. Length of cell along apical axis 10-61 µm. Valves distinctly sculptured, with puncta in more or less regular radial rows running outward from center toward processes, 16-20 puncta in 10 µm. Sculpturing on intercalary bands visible only under high magnification,28-33 rows of puncta in 10 µm. Chromatophores small and numerous. Minute, highly refractive, colorless granules present in ends of processes (Cupp, 1943).
Cells length 40-65 µm.
Neritic, south temperate species; very widely distributed.
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 (3.5*10^4 cells/l) was associated with the Sea of Oman (St. 93). It has been previously reported from the inner RSA (Simonsen, 1974) and from Kuwaiti waters (Al-Yamani et al., 2004; Al-Kandari et al., 2009).