Volachlamys Iredale, 1939

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 : 296

Volachlamys Iredale, 1939

Volachlamys Iredale, 1939: 356 . Type species (by original designation): Pecten cumingii Reeve, 1853 (= Pecten singaporinus G. B. Sowerby II, 1842 ); Recent, Queensland.

Diagnosis. Medium-sized Mimachlamydini with circular shape in late ontogeny, valves relatively flattened; macrosculpture of evenly spaced, prominent radial plicae and commarginal lamellae throughout ontogeny, with shallowly pitted microsulpture on pre-radial area of left valve and interstitial scaly imbricate “pseudo-shagreen” microsculpture in the early radial stage, weak interstitial radial microsculpture present late in ontogeny of some specimens; internal rib carinae prominent around ventral margin; resilial teeth weak, dorsal teeth prominent, narrow; byssal notch deep, ctenolium well-developed.

Distribution. Miocene(?)–Recent (Hayami, 1989). Tropical Indo-West Pacific, living in the littoral to sublittoral zones on soft sediment.

Discussion. Hertlein (1969: N357) treated Volachlamys as a junior synonym of Argopecten Monterosato, 1889 , a subgenus of Chlamys , placed in the suprageneric Chlamys group.

The extant tropical Indo-West Pacific genus Volachlamys resembles the tropical eastern Pacific and western Atlantic genus Argopecten , although it differs in convexity of the valves (more flattened in Volachlamys and more strongly convex in Argopecten ) and in microsculpture. Volachlamys has interstitial imbricate “pseudo-shagreen” microsculpture in the early radial stage, whereas Argopecten has radial microsculpture. As noted above, Volachlamys also has a weakly pitted pre-radial area of the left valve, as in Mimachlamys and Minnivola , whereas this area is more deeply pitted in Aequipectinini . Volachlamys is included here in tribe Mimachlamydini ; the resemblance to Argopecten is a further confusing convergence produced by similarities in habit rather than by close phylogenetic relationship (T. R. Waller, USNM, pers. comm. 1 July 2017).