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 : 633-635

“ Acteon ” sp. 3

Figs 22C, 23

MATERIAL EXAMINED. — Loyalty Ridge. BIOCAL: stn DW 80 , 20°32’S, 166°48’E, 900-980 m, 1 dd (Fig. 22C) . — CALSUB:

PL 12, E of Thio, 21°28’S, 166°21’E, 700-1200 m, 1 dd.

DISTRIBUTION. — Collected only in New Caledonia (Fig. 23), in 900-980 m.

DESCRIPTION. — Shell morphology. Length 4.5 mm, width 2.5 mm (largest specimen examined). Shell thin, fragile, elongate, with convex sides (Fig. 22C). Body whorl large, about 4/5 of the shell length. Spire elongate, conical, with 2 whorls. Suture slightly channeled. Umbilicus closed. Aperture wide and short, wider anteriorly, about 3/4 of the body whorl length. Columellar margin slightly thickened, short, with a small fold. Sculpture of a number of punctuated

FIG. 22. Shell morphology of unidentified species of “ Acteon ”. A, “ Acteon ” sp. 1, (7 mm), ventral view, New Caledonia, BIOGEOCAL stn DW 313. B, “ Acteon ” sp. 2, (3.2 mm), ventral view, Philippines, MUSORSTOM 2 stn DR 34. C, “ Acteon ” sp. 3, (4.5 mm), ventral view, New Caledonia,BIOCAL stn DW 80. D, “ Acteon ” sp. 4, (10 mm),ventral view, Banc Combe, MUSORSTOM 7 stn DW 540. E, “ Acteon ” sp.5,(4 mm), ventral view, Tonga, BORDAU 2 stn DW 1552. F, “ Acteon ” sp. 6, (3.5 mm),ventral view, New Caledonia,SMIB 8 stn DW 146-147. G, “ Acteon ” sp. 7, (8 mm), ventral view, Philippines, ESTASE 2 stn DW 1. H, “ Acteon ” sp. 8, (9 mm), ventral view, New Caledonia, BATHUS 4 DW 885.

spiral grooves. The punctuations are small, oval, and fused to the next one within each groove. The grooves are separated by large gaps that increase in width towards the posterior end of the spire. Colour uniformly dirty white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — “ Acteon ” sp. 3 most resembles Acteon chrystomatus n. sp. in shell morphology. Differences between them include the more elongate shape of the shell of “ Acteon ” sp. 3, which also has narrower spiral grooves separated by wider gaps and lacks any pigment on the shell.

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