Bacillaria paxillifera (O.F. Müller) Hendey

Division: Chromophyta
Class: Bacillariophyceae
Order: Bacillariales
Suborder: Bacillariineae
Family: Bacillariaceae Ehrenberg
Genus: Bacillaria Gmelin
Scientific name: Bacillaria paxillifera (O.F. Müller) Hendey

Genus is characterized by the presence of a canal raphe. Number of fibulae and striae, and the quotient between them are important characters at species level. Genus Bacillaria does not belong to plankton primarily; B. paxillifera, however, is often found in samples from shallow areas (Throndsen et al, 2007).

Synonyms:
Bacillaria paradoxa Gmelin; Nitzschia paradoxa (Gmelin) Grunow ex Cleve et Grunow

References:
Pavillard, 1925: p. 62, Fig. 112 (as Bacillaria paradoxa); Allen and Cupp, 1935: p. 161, Fig. 117 (as Bacillaria paradoxa); Cupp, 1943: p. 206, Fig. 159 (as Nitzschia paradoxa); Hendey, 1964: p. 274, Pl. XXI: 5; Simonsen, 1974: p. 49 (as Bacillaria paradoxa); Ricard, 1 987: p. 281, Figs. 1125-1128 (as Bacillaria paradoxa); Throndsen et al., 2007: p. 192.

Description:
Cells united into movable colonies, the cells sliding along one another. In girdle view rectangular. In valve view linear-lanceolate with produced ends. Keel nearly central. Keel puncta 7-9 in 10 µm. Striae 20-21 in 10 µm. Length of valves 80-115 µm; width 5-6 µm.Chromatophores small, numerous. Nucleus central (Cupp, 1943).

Dimensions:
Cells length 120-135 µm; width 6-7 µm.

Distribution:
Very common in plankton.

Sites of occurrence in RSA:
In Winter 2006 Cruise, this species occurred, usually in small numbers, however, it was quite abundant at some localities (refer sites map); maximum abundance (1.2*10^3 cells/l) was associated with Kuwaiti waters in the northwestern part of the inner RSA (St. 1). Species have been previously reported (as Bacillaria paradoxa) from the inner RSA (Simonsen,1974) and from Kuwaiti waters (Al-Yamani et al., 2004; Al-Kandari et al., 2009).