Family: Rhizosoleniaceae De Toni
Genus: Proboscia Sundström
Scientific name: Proboscia alata f. gracillima (Cleve) Licea et Moreno
Rhizosolenia alata var. gracillima Cleve; Rhizosolenia alata form gracillima (Cleve) Grunow; Rhizosolenia gracillima Cleve
Hustedt, 1930: p. 601, Fig. 345 (as Rhizosolenia alata f. gracillima); Allen and Cupp, 1935: p. 130, Fig. 44 (as Rhizosolenia alata f. gracillima); Cupp, 1943: p. 92, Fig. 52 B (as Rhizosolenia alata f. gracillima); Crosby and Wood, 1958: p. 520, Pl. 38: 62 b (as Rhizosolenia alata f. gracillima); Hendey, 1964: p. 146, Pl. II: 3 (as Rhizosolenia alata f. gracillima).
Like the type, but narrower. Diameter 4-7 µm. Production of auxospores bring it to same size as the type (Cupp, 1943).
Non-toxic, but harmful bloom-forming species. Harmful effects have been recorded in 1983 within South China Sea: a large loss of fish, shrimp, and shellfish was reported, resulting in reduction of fish mariculture outputs (in one country alone, Gaoyang, 75 tons of fish-kill) (Yan et al., source: web-site).
Cells length 320-480 µm; diameter 6-9 µm.
Coastal form, perhaps truly neritic.
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 (4.9*10^3cells/l) was associated with the Iranian coast in the northwestern part of the inner RSA (St. 11a). It has been previously reported from Kuwaiti waters of the inner RSA (Al-Kandari et al., 2009).