Acteon, Montfort, 1810

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 641-642

“ Acteon ” sp. 13

Figs 24E, 25

MATERIAL EXAMINED. — Loyalty Ridge. BIOGEOCAL: stn CP 232, 21°34’S, 166°27’E, 760-790 m, 2 dd.

DISTRIBUTION. — Collected only from New Caledonia (Fig. 25), in 760-790 m.

DESCRIPTION. — Shell morphology. Length 4 mm, width 2 mm (largest specimen examined). Shell fragile, elongate, with convex sides (Fig. 24E). Body whorl large, about 4/5 of the shell length. Spire elongate, conical, with 2 long whorls. Suture slightly channeled. Umbilicus closed. Aperture short and wide, wider anteriorly, between 1/2 and 2/3 of the body whorl length. Columellar margin slightly thickened, with a single inconspicuous fold. Sculpture of several punctuated spiral grooves. The punctuations are very small, oval, and fused to the next one within each groove. The grooves are separated by gaps, several times wider than the grooves. Colour uniform dirty white to pale grey.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — “ Acteon ” sp. 13 is similar to Acteon chrystomatus n. sp. in shell morphology. Both species have elongate shells with small apertures. The main difference between them is in the sculpture, which is composed of spiral grooves with large punctuations and 2 distinct spiral grooves situated near the posterior end of the spire with very elongate punctuations in A. chrystomatus , whereas in “ Acteon ” sp. 13 the sculpture is composed of spiral grooves with small punctuations, all of similar size. The sculpture of “ Acteon ” sp. 13 resembles that of Bathyacteon aequatorialis (Thiele, 1925) , but the shell of the latter is much shorter with a larger aperture and a small spire. “ Acteon ” sp. 13 is probably a distinct species of Acteonidae but it is not named here because of the lack of enough material.

A definitive generic placement for this species is not possible until complete specimens become available for study.