Semipallium dringi (Reeve, 1853)

Dijkstra, Henk H. & Beu, Alan G., 2018, Living Scallops of Australia and Adjacent Waters (Mollusca: Bivalvia: Pectinoidea: Propeamussiidae, Cyclochlamydidae and Pectinidae), Records of the Australian Museum (Rec. Aust. Mus.) 70 (2), pp. 113-330 : 263-264

Semipallium dringi (Reeve, 1853)

Figs 78G,I, 79, 80C,E,J

Pecten dringi Reeve, 1853 : sp. 152, pl. 33, fig. 152b; E.A. Smith, 1884: 115 (in part); Küster & Kobelt, 1888: 207, pl. 55, figs 7–8 (in part).

Chlamys dringi (Reeve) .–Dautzenberg & Bouge, 1933: 426 (in part).

Semipallium kengaluorum Dijkstra, 1986: 24 , figs.

Semipallium fulvicostatum (A.Adams &Reeve,1850) .– Wagner, 1989b: 114 (lectotype designation; misidentification).

Semipallium dringi (Reeve) .–Dijkstra, 1991: 39; Raines & Poppe, 2006: 240–241, upper figs; pl. 191, figs 1–7; Dijkstra & Moolenbeek, 2008: 20; Huber, 2010: 207; Raines, 2010: 634, pl. 1008, figs 1–7; Dijkstra, 2013: 81, pl. 21, figs 3a–d, pl. 30, figs 3a–b.

Chlamys (Complicachlamys) dringi (Reeve) .–Wells, Slack- Smith & Bryce, 2000: 42.

Complicachlamys dringi (Reeve) .–Dharma, 2005: 250, pl. 100, figs 11a–d.

Type data. Pecten dringi Reeve : lectotype (pr) NHMUK 1950.11 .14.28, designated by Wagner (1989b: 114, fig. 5), 2 paralectotypes (pr) NHMUK 1950.11.14.29–30. Type locality: Australia, Northern Territory, Bathurst Island .

Semipallium kengaluorum Dijkstra : holotype (pr) ZMA Moll.386024, 8 paratypes (pr): NHMUK1987056 , 1 MNHN21273 , 1 RMNH.MOL.55994, 1 USNM859393, 4 ZMA Moll.3.86.025 (2), 3.86.026 (2). Type locality: Solomon Islands , Russell Island , alive, 35 m.

Comments on type data. For information on type material of Semipallium dringi and comparison with S. kengaluorum see Dijkstra (1991: 39).

Additional material examined. — AUSTRALIA: QUEENSLAND: GBR,S end of Lizard Island, The Lagoon, coral reef near South Island ,dead, 2–3 m (1 pr, R.C.Willan colln) . WESTERN AUSTRALIA: North West Shelf, 45 n. ml NNE of Port Hedland, 19°55.2'– 19°55.6'S 117°56.0'– 117°55.6' E, dead, 40 m (1 v,C.157712); North West Shelf, 52 n. ml NNE of Port Hedland, 19°30.9'– 19°28.2'S 118°49.2'– 118°55.4'E, dead, 36–37 m (1 v, C.157681;1 v, C.157682); North West Shelf , 78 n. ml NNE of Port Hedland,19°04.6'– 19°04.3'S 118°47.4'– 118°47.6'E,dead, 82 m (1 v, C.149223); North West Shelf , 78 n. ml NNE of Port Hedland, 19°04.4'– 19°04.2'S 119°04.4' – 119°00.7'E, dead, 82 m (1 v,C.157692); North West Shelf , 80 n. ml NNE of Port Hedland, 19°03.6' – 19°03.4' S 119°03.4'– 119°03.5'E, dead, 82 m (many v, C.146786); in rubble at base of vertical wall of coral,near NE entrance, Mermaid Reef , Rowley Shoals ,off Broome ,dead, 33 m (1 pr, HM) .— CHRISTMAS ISLAND: 10°30'S 105°40'E, dead (1 pr,C.374866); sand and rubble, Flying Fish Cove ,dead, 8 m (1 pr, HM). CORAL SEA: Flinders Cay, dead, dredged 35–50 m (1 pr, HM) .— PHILIPPINE ISLANDS : Masbate,alive, 15–20 m (1 pr, ZMA Moll. 146369) . — INDONESIA: Alor Islands , Ternate Island, S end, dead, 5 m (1 pr, ZMA Moll. 146198;1 pr HM) .— MARSHALL ISLANDS : Kwajalein Atoll,alive, 12 m (1 pr, ZMA Moll. 146546) .— PAPUA NEW GUINEA: Port Moresby, Bootless Bay , 9°30'S 147°15.5'E, alive, 20 m (1 pr, NTM P005577 ) .— FIJI ISLANDS : Viti Levu, Beqa Island , alive, 27 m (1 pr, ZMA Moll. 144567) .

Description. Shell up to 66 mm high (Huber, 2010), most specimens smaller, to 30 mm; weakly inflated, left valve slightly more convex than right, subcircular, somewhat higher than wide, almost equivalve and equilateral, auricles highly unequal in shape and size, umbonal angle c. 90°; colour variable, creamy-orange with purple, yellow or pale cream blotches, right valve paler and with yellow blotch near umbo.

Both valves sculptured with 9 evenly spaced radial plicae; plicae each bear 5 prominent secondary radial riblets; 3–4 weaker secondary riblets in interplical spaces. Secondary riblets on right valve bear delicate, closely spaced commarginal lamellae. Shagreen microsculpture present in radial interspaces. Anterior auricles larger and longer than posterior, bearing 8–10 radial costae on left valve and 5–6 on right; posterior auricles almost smooth. Byssal notch moderately deep, byssal fasciole broad. Functional ctenolium well-developed, with 5–7 teeth. Internal plicae with edges carinate around ventral margin. Hinge with weak resilial and dorsal teeth.

Dimensions. Illustrated specimens: In rubble at base of vertical coral wall, 33 m, near NE entrance, Mermaid Reef, Rowley Shoals, off Broome, WA, dead (pr, HM); rv: H 38.3, L 35.0 mm; lv: H 38.8, L 34.1 mm; D 8.2 mm. Other large specimen: sand and rubble, Flying Fish Cove, Christmas Island, dead, 8 m (pr, HM); rv: H 42.2, L 39.6 mm; lv: H 43.3, L 39.4 mm; D 11.4 mm.

Habitat. Living in the littoral to sublittoral zones, byssally attached to undersides of coral slabs or boulders or amongst coral rubble on clean sandy bottoms.

Distribution. Tropical Indo-West Pacific, from the Philippines southwards to northern Australia and eastwards into the central Pacific to the Marshall and Fiji Islands (Raines & Poppe, 2006: 240); Philippines to Indonesia, 18–56 m (Huber, 2010: 207); Philippines, 7–80 m ( Raines, 2010: 634; Dijkstra, 2013: 81); Indonesia (Dijkstra & Moolenbeek, 2008: 21). Maximum depth range of live-taken specimens is 7– 80 m. Present specimens from Australia dead at 2– 82 m.

Remarks. Semipallium dringi has been identified under different names by several previous authors, before Wagner (1989b) designated a lectotype for Pecten dringi . The type lot includes specimens of two nominal taxa, Semipallium dringi and Complicachlamys wardiana Iredale, 1939 . Semipallium dringi was also synonymized with S. fulvicostatum (A.Adams & Reeve, 1850) by Wagner (1989b), but S. fulvicostatum differs from S. dringi by having a more strongly prosocline shape ( S. dringi is subcircular), coarser and more prominent shagreen microsculpture throughout (intercostal only in S. dringi ), antimarginal microsculpture laterally (lacking in S. dringi ), and in its coloration ( S. dringi is more polychrome).