Moerella laperousea, Raines & Huber, 2012

Raines, Bret & Huber, Markus, 2012, 3217, Zootaxa 3217, pp. 1-106 : 76-78

Moerella laperousea sp. nov.

Figures 39 A–F

Type Material. Holotype: LACM 3169, 1 articulated specimen, 10.5 mm. Paratypes 1–4: LACM 3170, 4 single valves from the type locality. Paratypes 5–6: LACM 3171, 2 articulated specimens, 4.5 mm from Tahai, 30–50 m. Paratypes 7–12: LACM 3172, 1 articulated specimen and 5 single valves, up to 12.5 mm from Tahai, 50–100 m. Paratypes 13–18: Coll. MHU, 1 articulated specimen and 5 single valves from Tahai, 50–100 m.

Type Locality. Dredged at 50–150 m in sand, La Perouse Bay, Easter Island, 27°04’26” S, 109°16’50” W .

Description. A finely commarginally sculptured, radially orange-red colored Moerella with the characteristic short and strong anterior lateral tooth in the RV and an opisthogyrate position of the umbones. Shell moderately small, not exceeding 13 mm, elongate-ovate, posteriorly with a weak flexure and obscurely rostrate; rather thin; white with 5–6 broad orange-red radial streaks, emanating from the umbones; internal posteriorly and in the nymphal area rose red in some, otherwise white; no lunule; umbones very low, small, opisthogyrate, situated at the posterior third of the valve. Prodissoconch round, moderately elevated, P1 somewhat pitted, ca. 118 µm length by 93 µm height, P2 with faint to weak commarginal lines, ca. 228 µm length by 185 µm height. Adult valves compressed. Sculpture of dense, regular, commarginal threads. Hinge line rather thin, in RV with a strong, bifid posterior and a weak anterior cardinal, a short, strong anterior lateral and a nymphal posterior lateral. LV with a single strong bifid cardinal, laterals thin and vanishing. Pallial sinus very deep, ventrally surpassing anterior adductor scar, confluent; both muscle scars are comparatively large. External ligament rather short and strong, resting on a nymph, yellowish-brown. Margins smooth.

Comparative diagnosis. With regard to placement of this new species, the commarginal sculpture and lateral dentition exclude Loxoglypta Dall, Bartsch & Rehder, 1938 , and the finer sculpture and lateral dentition exclude Nitidotellina Scarlato, 1965 , as well. The hinge with a pronounced anterior lateral in the RV, vanishing laterals in the LV and the deep, confluent pallial sinus, together with shape, size and sculpture match the European type species of Moerella quite well. This assessment was shared by A. Langleit, (pers. comm., 2010). None of the illustrated Moerella species from Australia, New Zealand or Japan are particularly close.

Remarks. There is nothing similar known from the Hawaiian Islands.

Distribution. Moerella laperousea is commonly found from 30–200 m in fine sand, at various Easter Island locations, notably off the western coastline near Tahai— E1.

Etymology. The name reflects the type locality.