Pseudamussium gilchristi (Sowerby, 1904)

Dijkstra, H. H. & Kilburn, R. N., 2001, The family Pectinidae in South Africa and Mozambique (Mollusca: Bivalvia: Pectinoidea), African Invertebrates 42, pp. 263-321 : 271-272

Pseudamussium gilchristi (G. B. Sowerby 3rd, 1904), comb. n.

( Figs 5–6 ) Chlamys gilchristi Sowerby, 1904: 1 , pl. 7, fig. 6; E. A. Smith, 1906: 59; Barnard, 1964: 427; idem, 1974:

761; Lussi, 1995: 2, 12, fig. 16. Type locality: 18.5 miles off Vasco da Gama Peak , N 71°E

(should be read as S 71°W), 230 fath. (421 m), stones.

5 6

Karnekampia gilchristi ; Wagner, 1988: 42, fig. 3 (holotype refigured); idem, (1991): 20.

Chlamys (Chlamys) gilchristi ; Rombouts, 1991: 12, pl. 24, fig. 2.

Description: Shell up to ca. 35 mm high, suborbicular, RV somewhat more convex than LV, equilateral, auricles unequal, umbonal angle ca. 90°. LV sculptured with 8 rounded primary radial lirae, RV with 9 broader and flatter primary radial lirae and numerous granulose secondary radial ribs (LV with 3 on main ribs, 4 interstitial; RV with 5 on main ribs, 2 interstitial) with very fine and close-set radial riblets near ventral margin, covered with a periostracal layer (often damaged in adult stages). Microsculpture in early ontogeny of antimarginal striae, more prominent near anterior and posterior margins.Anterior auricle of LV with 4–6 lamellose radial and concentric ribs (cancellated in early ontogeny), on posterior with 3–4 weaker granulose radial riblets. Hinge line straight. Byssal fasciole rather broad, byssal notch narrow, active ctenolium with 5–7 teeth on suture. Auricular crura small, resilifer triangular. Colour orange or pinkish, internally glossy orange-yellow or reddish-orange.

Type material: Holotype SAM 14853 (seen by HD).

Regional data (all NMSA unless otherwise stated): NAMIBIA: off Walvis Bay, ca. 200 m, trawled, attached to old netting & ropes, live (K3888: S. Whatmough). SOUTH AFRICA: Atlantic Cape: off Cape Columbine, trawled, dead (B6700: R. Cruickshank); 26 km W of Kleinzee (S of Port Nolloth), 130 m, dead (E7221: J. Pether); 31°14'S; 16°36'E, 272 m ( SAM) .

Unconfirmed: A gulhas Bank: off Port Elizabeth, 200 m, trawled in mud balls, dead (E3100: S. Whatmough).

Distribution: Continental shelf of Namibia and Atlantic Cape.

Habitat: Bathyal depths (ca. 130–420 m), substrate not established.

Remarks: Wagner (1988: 42) referred P. gilchristi to his new genus Karnekampia , whose characters essentially agree with those of Pseudamussium .

Figures

Figs 5–6. Pseudamussium gilchristi (Sowerby, 1904): NMSA E3100, Agulhas Bank, 200 m, pv, 30.8 x 31.1 mm. 5. LV exterior. 6. RV exterior.