Semipallium, Lamy, 1928

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 : 260

Key to species of Semipallium from Australia

1 Shell c. 42 mm high, elongate, moderately prosocline, weakly inflated, valves almost equally convex, auricles highly unequal, lv with 9–11 narrow, widely spaced radial costae, rv more subdivided into 18–20 narrow costae, shagreen microsculpture throughout, byssal notch deep, byssal fasciole narrow, ctenolium well-developed ............................................................................................ S. aktinos

—— Shell with 8–10 radial plicae with shagreen microsculpture ..................................................... 2

2 Shell c. 50 mm high, elongate, weakly infated, lv slightly more convex than rv, auricles highly unequal, valves with 8–10 evenly spaced radial plicae with shagreen microsculpture, byssal notch deep, byssal fasciole broad, ctenolium well-developed ............................................... S. dianae

—— Shell with 9 primary radial plicae with secondary riblets ......................................................... 3

3 Shell c. 30 mm high, subcircular, weakly inflated, lv more convex than rv, auricles highly unequal, valves with 9 primary radial plicae, secondary radial riblets on plicae and interspaces, shagreen microsculpture in interspaces, byssal notch deep, byssal fasciole broad, ctenolium well-developed ..................................................................... S. dringi

—— Shell with 8–10 radial plicae with scaly radial riblets ............................................................... 4

4 Shell c. 60 mm high, subtriangularly ovate, prosocline, rather inflated, rv more convex than lv, auricles highly unequal, valves with 8–10 evenly spaced radial plicae, scaly radial riblets on plicae and interspaces, byssal notch deep, byssal fasciole broad, ctenolium well-developed ......................................................................................... S. flavicans

—— Shell with 9 primary radial plicae with 5 secondary radial riblets ............................................... 5

5 Shell c. 60 mm high, elongate and prosocline, weakly inflated, lv slightly more convex than rv, auricles highly unequal, valves with 9 evenly spaced primary radial plicae, secondary radial riblets on plicae and interspaces, byssal notch deep, byssal fasciole broad, ctenolium well-developed .......................................................... S. fulvicostatum

—— Shell with 8–9 narrow on lv and wide on rv weakly dedined radial plicae ......................................................................................................................................... 6

6 Shell c. 55 mm high, elongate, almost equally convex, auricles unequal, valves with 8–9 evenly spaced, weakly defined primary radial plicae, narrow on lv, wide on rv, secondary radial riblets on plicae and interspaces, interstitial shagreen microsculpture, byssal notch deep, byssal fasciole broad, ctenolium weakly developed ......................................................................................... S. hallae foulcheri ( Tenison Woods, 1865), occurring in the Willungan (= lower Oligocene) part of the Port Willunga Formation, South Australia, and up to Balcombian (middle Miocene) (Beu & Darragh, 2001, p. 69) is the earliest species we know of. Tropical Indo-West Pacific and temperate Australia, living in the littoral to sublittoral zones among coral or coral rubble on soft sediment (usually sand).