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 : 635

“ Acteon ” sp. 4

Figs 22D, 23

MATERIAL EXAMINED. — Wallis and Futuna. MUSORSTOM 7: stn DW 540 , Banc Combe , 12°27’S, 177°28’W, 600 m, 1 dd .

DISTRIBUTION. — Single shell collected in the Wallis and Futuna region (Fig. 23), in 600 m.

DESCRIPTION. — Shell morphology. Length 10 mm, width 5.5 mm (the only specimen examined). Shell solid, elongate, with convex sides (Fig. 22D). Body whorl large, about 2/3 of the shell length. Spire long, conical, with 5 whorls. Suture channeled. Umbilicus closed. Aperture long and narrow, wider anteriorly. The aperture is about 3/4 of the body whorl length. The anterior end of the aperture is expanded into a very short lip. Columellar margin thickened, slightly oblique, with no folds. Sculpture of a number of punctuated spiral grooves. The punctuations are large, oval, partially fused to the next one within each groove. The grooves are separated by gaps that are several times wider than the grooves. Colour uniform dirty white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — “ Acteon ” sp. 4 resembles “ Acteon ” boteroi n. sp. in shell shape, but it is clearly differentiated by having larger punctuations in the sculpture. Another similar species is Maxacteon cf. kawamurai , which also has a solid shell with large spiral punctuations. Differences between these two species include the presence of an umbilicus in M. cf. kawamurai and the larger gaps between the spiral grooves in “ Acteon ” sp. 4.

There are no other Indo-Pacific species of Acteonidae similar to “ Acteon ” sp. 4, and it is likely that it is an undescribed species. However, it is not named here because of the lack of sufficient material.

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