Myonera sp.

Raines, Bret & Huber, Markus, 2012, 3217, Zootaxa 3217, pp. 1-106 : 93-94

Myonera sp.

Figures 48 A–D

Material examined. A single RV, 7.5 mm (BK).

Description. Shell small (7.5 mm in length), thin, fragile, somewhat inflated, ovate, with pronounced posterior rostrum. Both anterior and posterior margins curved. Umbones elevated above the hinge line. Exterior surface with rather widely spaced commarginally lamellate sculpture, ridge separating the rostrum. Interior smooth. Hinge simple and edentate. Color translucent white.

Remarks. The shape, thin structure, commarginally lamellate sculpture, a ridge separating the rostrum, together with an edentate hinge approaches the damaged USNM syntypes of Myonera pailoloana ( Dall, Bartsch & Rehder 1938) . The latter is known from two valves from 915 m off the Pailolo Channel, Hawaii. The better preserved syntype is illustrated in Severns (2011: 486, pl. 223, fig. 1). [Note: Dall et al. (1938) 's type material, differs in shape, size and sculpture from the specimen illustrated in Kay (1979: pl. 191, fig. H)].

Although the EI species measures about half the size of the largest M. pailoloana syntype, the lamellar ridges appear to be fewer in number, wider spaced and fading ventrally. The shape seems to be more elongate and the rostrum comparatively longer as well. The Hawaiian material was dredged dead from 915 m, whereas the EI material was found much shallower from approximately 50–80 m.

Myonera tasmanica ( Knudsen, 1970) , from New Zealand was also considered. However, here too, the rostrum is shorter, the shape higher and the sculpture denser. Furthermore, M. tasmanica was described from an abyssal depth of 4,390 m. The EI species cannot be confused with any of the other known Indo-Pacific and Hawaiian Myonera , notably, M. bicarinata E.A. Smith, 1896 , M. dautzenbergi Prashad, 1932 , M. dispar ( Dall, Bartsch & Rehder, 1938) , M. lischkei (E.A. Smith, 1891) , and M. rostra Poutiers & R.F. Bernard, 1995 , due to the stronger sculpture and/or shorter rostration.

In all likelihood this is an undescribed Myonera species , endemic to the waters of EI. However, due to the limited amount of EI material and the unknown variability of M. pailoloana a formal description is premature. This species is illustrated and treated as endemic, awaiting further finds.

Habitat. Dredged at 50–80 m in sandy mud, off the western coastline near Tahai , Easter Island, 27°07’20” S, 109°26’30” W .

Distribution. At present this Myonera sp. is only known from Easter Island— E1.