Hemiaulus membranaceus Cleve

Division: Chromophyta
Class: Bacillariophyceae
Order: Biddulphiales
Suborder: Biddulphiineae
Family: Hemiaulaceae Heiberg
Genus: Hemiaulus Ehrenberg
Scientific name: Hemiaulus membranaceus Cleve

 

Species: membranaceus

References:
Allen and Cupp, 1935: p. 150, Fig. 90; Cupp, 1943: p. 170, Fig. 120; Crosby and Wood,1958: p. 510, Pl. 36: 25; Simonsen, 1974: p. 33; Ricard, 1987: p. 187, Fig. 330.

Description:
Cells in girdle view from almost square to five or six times wider (length along apical axis) than long (length along pervalvar axis). Valves concave or nearly flat between processes. Processes short, with a more or less sharp point; united in chains by processes. Apertures narrow, linear to elliptical, or even broadly elliptical. Cell wall weakly siliceous. Punctation on valves very fine, difficult to see. Length of apical axis 30-97 µm (Cupp, 1943).

Dimensions:
Cells length 45-60 µm; width 25-32 µm.

Distribution:
Tropical oceanic species; reported in eastern Pacific only from near equator (lat. 3°150 S.)
(Cupp, 1943).

Sites of occurrence in RSA:
In Winter 2006 Cruise, this species occurred occasionally at various sites (refer sites map),usually in small numbers; however, it was quite abundant at some localities; maximum abundance (3.9 103 cells/l) was associated with the Sea of Oman (St. 88). species have been previously reported from the inner RSA (Simonsen, 1974) and from Kuwaiti waters (AlYamani et al., 2004; Al-Kandari et al., 2009).