Volachlamys fultoni (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 : 314-315

Volachlamys fultoni (G. B. Sowerby 3rd, 1904)

(Figs 54–55)

Chlamys fultoni Sowerby, 1904: 2 , pl. 7, fig. 5; E.A. Smith, 1906: 59; Barnard, 1964: 428, fig. 14a; Boshoff,

1965: 134, pl. 14, fig. 7; Kilburn & Rippey, 1982: 171, pl. 38, fig. 11. Type locality: 7.5 mi. ‘N.

W.’ (= SE) of Conical Hill , Amatikulu, Zululand, South Africa, 26 fath. (= 48 m), muddy bottom. Pecten fultoni ; Hayami, 1985: 5 .

Volachlamys fultoni ; Anonymous 1991: 2, fig. 6; Rombouts, 1991: 62, pl. 5, fig. 6.

Argopecten fultoni ; Steyn & Lussi, 1998: 212, fig. 857.

Chlamys eucosmia (non Turton, 1932); Boshoff, 1965: 136, pl. 14, fig. 9.

Description:Shell up to 40 mm high, usually somewhat smaller, compressed, suborbicular, nearly equivalve, equilateral, auricles slightly unequal, umbonal angle ca. 90°. Both valves with numerous prominent radial plicae (16–18, usually 17), which are somewhat squamose near ventral margin, and fine, closely spaced, commarginal lamellae in interstices on RV and in late ontogeny on left; granular microsculpture in interstices and sometimes on posterior auricle of LV; lamellae and microsculpture variable in development, sometimes almost absent (Barnard 1964: 429). Auricles with 5–7 small radial riblets, somewhat nodulous, and fine, closely spaced, commarginal lamellae on anterior auricle of LV, more coarsely laminated on anterior auricle of right. Byssal fasciole moderately wide, byssal notch deep. Active ctenolium well developed with 4–6 teeth on suture. Inner surface slightly plicated to more angulated near ventral margin. Cardinal crura weak. Resilifer oblong, oblique; resilial denticles absent. Colour variable, creamy-brown, purplish-brown with white or cream blotches or streaks, sometimes almost uniform brown or white.

54 55

Figs 54–55. Volachlamys fultoni (Sowerby, 1904) : HD 5826, Catembe, Mozambique, pv, 34.5 x 35.0 mm. 54. LV exterior. 55. RV exterior.

Type material: Lectotype (H 33.5 mm, L 33 mm, D 11 mm) BMNH 1904.12 .23.164 herein designated; paralectotype (LV) SAM 14970 .

Regional data: MOZAMBIQUE: off Maputo, 120 m, muddy sand, live ( HD6471 ); Maputo, beach drift (5004); Beira, reclamation dump, dead (J5112, G8177: E. Roscoe). SOUTH AFRICA: Zululand: off Neill Peak (Cunge), 50 m, mud, dead (E3881); Tugela Bank, 41 m, fine mud, dead (A7158); off Matigulu River mouth, 70 m, coarse sand, broken shell, dead (S744); off Tugela Bluff, 60–65 m, mud, dead (E9060). Natal: off Mvoti River mouth, 70 m, soft mud, dead (E9159); off Sheffield Beach , 50 m, fine sandy mud, dead (E9247); same loc., 50 m, fine sand, dead (E9598); SE of Sheffield Beach, 50 m, sandy mud, dead (E5082); off Tongaat Bluff, 50 m, mud, dead (E9941); same loc., 50 m, soft mud, algal debris, dead (S180, S181); off Durban, 274 m, dead (9934); Durban Bay , shallow dredgings (B1663); off Isipingo, 55 m, dead (B3045); off Umlaas Canal, 50 m, fine sand, dead (D1046). TRANSKEI: off Mbotyi, 45 m, mud, dead (C7129); off Mzimhlava R., 50 m, clay, thick mud, dead (C7120); off Mgazi, 48 m, mud, dead (C3268); off N’tafufu River, 50 m, mud, sand, dead (C1039). Eastern Cape region: off East London , 70 m, muddy sand, schizamminid forams, dead (B8330); same loc., 70 m, muddy sand with lumps of black mud, dead (B8274); same loc., 70 m, fine sand, broken shells, dead (B8414, B8460) .

Distribution: Central Mozambique to the eastern Cape, South Africa, also Malagasy Republic.

Habitat: Living byssally attached to rocks, or free, on muddy bottoms on continental shelf, living mainly in 40–70 m, sometimes deeper.

Remarks:A specimen identified as Chlamys eucosmia in the Boshoff collection in NMSA is actually a juvenile of the present species.

Volachlamys fultoni closely resembles V. tranquebaria ( Gmelin, 1791) from N and NE Indian Ocean, but the latter species is more convex and more oblong, and is sculptured with more numerous radial plicae (18–20) but fewer secondary interstitial radial riblets; it is also more brightly coloured. Granular microsculpture is also present in early ontogeny in V. tranquebaria , and (more strongly) in V. cumingii (Reeve, 1853) . Smooth individuals such as occur in the Japanese V. hirasei (Bavay, 1904) have never been observed in V. fultoni .