Pristigloma alba Sanders & Allen, 1973

Benaim, Natalia Pereira & Absalao, Ricardo Silva, 2011, Microgloma Sanders & Allen, 1973 (Nuculanidae) and Pristigloma Dall, 1900 (Pristiglomidae) (Pelecypoda) in the Campos Basin of Brazil, ZooKeys 152, pp. 1-20 : 5-7

Pristigloma alba Sanders & Allen, 1973 Figs 3-8

Pristigloma alba Sanders & Allen, 1973: 245, fig 5; Allen 2008: 67, 87, 95, 97-101, 103, 111, 113, 119, 141, 146, 152, 153, 157, 167, 168, 173. Oliver et al. 2009: figs. MO11691-11697 (available online).

Type specimen.

MCZ 271976. We tried to find this lot in the MCZ with the help of Mr. Cleo Oliveira, but the curators could not find it. We made contact with Dr John A. Allen who sent us live specimens from Surinam Basin #293 (08°58'N54°04'W, 1518 m) to compare with Campos Basin specimens. Furthermore, using the good description in Sanders and Allen (1973) and figures of the specimens of Rockall Trough and Biscay Bay available in Oliver et al. (2009) we could properly identify our specimens.

Geographical distribution.

Angola, 3739-4597 m; Canaries, 6709-6711 m; North America, 2178-4892 m; Brazil, 3459 m; Argentina, 4382-4405 m (all from Sanders and Allen 1973); Cape Verde, 3495 m; Angola, 3797 m; Canaries, 2351-3000 m; West Europe, 2897-4660 m; Newfoundland, 4400 m; North America, 2178-4833 m; Surinam, 5100 m; Brazil, 3495 m; Argentine, 4402 m (all from Allen 2008); Rock all Trough and Biscay Bay mostly in depths over 2000 m ( Oliver et al. 2009); Brazil–Campos Basin, 1200-1972 m (present study).

Material examined.

MNRJ 19114 (# 68, 2003), 4 valves; MZUSP 99977 (# 68, 2003), 4 valves; IBUFRJ 16161 (# 68, 2002), 3 valves; IBUFRJ 19001 (# 10, 2002), 5 valves; IBUFRJ 19002 (# 42, 2002), 3 valves; IBUFRJ 19003 (# 47, 2002), 1 valves; IBUFRJ 19004 (# 48, 2002), 7 valves; IBUFRJ 19005 (# 52, 2002), 1 valve; IBUFRJ 19006 (# 58, 2002), 6 valves; IBUFRJ 19007 (# 62, 2002), 3 valves; IBUFRJ 19008 (# 63, 2002), 6 valves; IBUFRJ 19009 (# 73, 2002), 14 valves; IBUFRJ 19010 (# 77, 2002), 2 valves; IBUFRJ 19011 (# 78, 2002), 4 valves; IBUFRJ 19012 (# 83, 2002), 2 valves; IBUFRJ 19013 (# 87, 2002), 6 valves; IBUFRJ 19014 (# 46, 2003), 1 valve; IBUFRJ 19015 (# 48, 2003), 15 valves; IBUFRJ 19016 (# 52, 2003), 1 valve; IBUFRJ 19017 (# 53, 2003), 16 valves; IBUFRJ 19018 (# 58, 2003), 3 valves; IBUFRJ 19019 (# 61, 2003), 2 valves; IBUFRJ 19020 (# 63, 2003), 16 valves; IBUFRJ 19021 (# 68, 2003), 14 valves; IBUFRJ 19022 (# 72, 2003), 1 valve; IBUFRJ 19023 (# 73, 2003), 8 valves; IBUFRJ 19024 (# 78, 2003), 14 valves; IBUFRJ 19025 (# 82, 2003), 1 valve; IBUFRJ 19026 (# 86, 2003), 4 valves.

Characterization.

Shell H/L ratio about 1.04. W/H ratio approximately 0.86. Muscle scars rarely visible; anterior adductor scar 2/3 of posterior scar. Anterior and posterior parts of the hinge plate usually of same length. Width of posterior row of teeth occupies about 65% of width of hinge plate, which is thin for its size (whp/H approximately 0.07). Posterior part of the hinge plate longer than anterior one. Prodissoconch smooth, with length approximately 120 µm.

Remarks.

This species was recently well described and for this reason we add only new information on the proportions of the shell (H/L and width) and hinge plate characteristics. Sanders and Allen (1973) noted no evident muscle scars or pallial line. In the Campos Basin specimens, no pallial line is discernible on the valves, but faint muscle scars are apparent in some specimens. It is a common species in the Atlantic, and its occurrence in the Campos Basin was expected, since it was previously recorded from the northern Brazilian coast (Pernambuco) and from Argentina. The present study provides new points to the geographical distribution of Pristigloma alba , and is also the shallowest (1200 m) record for the species, which was previously known only from abyssal depths (2100-4898 m).