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 : 621

“ Acteon ” loyautensis n. sp.

Figs 15, 16C-D, 17B

TYPE MATERIAL. — Holotype MNHN 20309 and 32 paratypes MNHN 20310-20312, 2 paratypes LACM 2982 .

TYPE LOCALITY . — Norfolk Ridge , 23°25’S, 167°53’E, 965 m [BIOCAL: stn DW 70 ] .

MATERIAL EXAMINED. — North of New Caledonia. BATHUS 4 : Loyalty Ridge. BIOGEOCAL: stn CP 232, 21°34’S, 166°27’E, 760- stn DW 914 , Grand Passage, 18°49’S, 163°15’E, 600-616 m, 2 dd. 790 m, 4 dd, paratypes ( MNHN 20311 ) .— MUSORSTOM 6: stn DW Norfolk Ridge. BIOCAL: stn DW 70 , 23°25’S, 167°53’E, 965 m, 7 468, 21°06’S, 167°33’E, 600 m, 2 dd, paratypes ( LACM 2982 ) .

dd, holotype ( MNHN 20309; Fig. 16C) and 6 paratypes ( MNHN Wallis Island. MUSORSTOM 7: stn DW 604, 13°21’S, 176°08’W, 20310). 415-420 m, 22 dd, paratypes ( MNHN 20312; Figs 16D, 17B).

DISTRIBUTION. — Known from New Caledonia and Wallis Island (Fig. 15), in 420-965 m.

DESCRIPTION. — Shell morphology. Length 9 mm, width 4.5 mm (holotype). Shell thin, elongate, with convex sides (Fig. 16C). Body whorl large, about 2/3 of the shell length. Spire very elongate, conical, with 3-4 long whorls. Suture channeled. Protoconch globose, wide, about 1 whorl and 800 Μm in diameter (Fig. 16D). Umbilicus closed. Aperture long, wider anteriorly, about 3/4 of the body whorl length. Columellar margin thickened, slightly oblique, with a small, inconspicuous fold. Sculpture of several punctuated spiral grooves (Fig. 17B). The punctuations are conspicuous, rounded, and fused together within each groove. The grooves are separated by gaps that increase in width towards the posterior end of the spire. The 2 grooves near the suture are closer to each other and the punctuations are larger than in the other grooves. Colour uniformly whitish.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — “ Acteon ” loyautensis resembles “ Acteon ” editus n. sp. in shell morphology. However, these two species are easily distinguishable by their sculpture, which is composed of conspicuous rounded punctuations in “ A. ” loyautensis and small, elongate punctuations in “ A. ” editus. In addition, in “ A. ” loyautensis the 2 grooves nearest the suture are composed of larger punctuations and are closer to each other than the rest, whereas in “ A. ” editus they are similar to the rest of the grooves in arrangement and size.

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

ETYMOLOGY. — Named after the Loyalty Ridge (Ride des Loyauté), situated south of the Loyalty Islands (Iles Loyauté) and New Caledonia, where part of the material here examined was collected.