Pedum spondyloideum ( Gmelin, 1791 )

Dijkstra, H. H. & Kilburn, R. N., 2001, The family Pectinidae in South Africa and Mozambique (Mollusca: Bivalvia: Pectinoidea), African Invertebrates 42, pp. 263-321 : 293-294

Pedum spondyloideum ( Gmelin, 1791)

(Figs 29–30)

Ostrea spondyloidea Gmelin, 1791: 3335 ; Dillwyn,1817:280. Type locality:‘India’ (here restricted to Maluku, Indonesia; ZMA).

Pedum spondyloideum ; Waller, 1972: 254, text figs 8, 21, 22, pl. 8, figs 136–143 (synonymy, description, distribution, ecology); Nielsen, 1986: 8, figs 3A–B (holotype refigured); Dijkstra & Knudsen, 1998: 79, pl. 5, figs 23–24 (further references, synonymy, type data, distribution).

Ostrea pedum Röding, 1798: 170 . Type locality: unknown.

Pedum pedum ; Roberts et al., 1982: 116, pl. 34, figs 7–7a.

Description: Shell height to ca. 100 mm, (averaging 50–70 mm), shape rendered extremely variable by mode of life, transversely oblong in juvenile stage, elongate in 29 30

Figs 29–30. Pedum spondyloideum ( Gmelin, 1791) : NMSA D9590 , between Bhanga Neck and Kosi Bay, Zululand , 6–18 m, pv, 36.5 x 23.4 mm. 29. LV interior. 30. RV exterior .

mature stage, RV more convex and laterally curved in mature stage, auricles of RV more distinct and unequal than of LV. LV with fine, irregularly spaced, scabrous radial riblets, very weak or absent near ventral margin in mature stage. Auricles not clearly differentiated. RV with microscopic scabrous radial riblets and laterally, closely spaced commarginal lamellae, more strongly developed near antero-marginal area in juvenile stage, smoother in late ontogeny. Dorsal margin of anterior auricle strongly curved, byssal fasciole broad, byssal notch rather deep, active ctenolium absent. Outer ligament strongly developed in ventral direction. Resilial insertion elongate, narrow and deflecting. Auricular crura absent. Colour whitish or creamy, with lateral and umbonal spots on RV, LV with purple or brown patches or streaks.

Type material: O. spondyloidea : holotype ZMUC BIV–57; seen by HD. Ostrea pedum : potentially in Museum der Natur at Gotha ( Dance 1986: 206), but not traced (Mrs M. Joost pers. comm.).

Regional data (all NMSA: D. Herbert et al.): SOUTH AFRICA: Zululand: between Bhanga Neck and Kosi Bay, No. 13 reef, 6–18 m, in coral, live (D9589, D9590); Kosi Bay, 20–24 m (S1751); Sodwana Bay, Two Mile Reef, 10–15 m, in coral, live (E678). Distribution: Coral reefs throughout the tropical Indo-Pacific, south-western limit northern Zululand.

Habitat: Living embedded in massive heads of scleractinian corals in shallow waters. Remarks: O. pedum Röding, 1798 , was based on an illustration in Favanne (1780: pl. 80, fig. K), which is similar to the type material of O. spondyloidea . The present specimens from South Africa also resemble the type material. For more information on morphology and ecology, see Yonge (1967: 311–323), Waller (1972: 254–258) and Kleemann (1990: 77–94).