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 : 640

“ Acteon ” sp. 10

Figs 24B, 25

MATERIAL EXAMINED. — Philippines. MUSORSTOM 2: stn DR 33, 13°32’N, 121°07’E, 130-137 m, 1 dd .

DISTRIBUTION. — Collected only from the Philippines (Fig. 25), in 130-137 m.

DESCRIPTION. — Shell morphology. Length 6 mm, width 3 mm in (single specimen examined). Shell fragile, elongate, with convex sides (Fig. 24B). Body whorl very large, about 6/7 of the shell length. Spire short, conical, with 3 short whorls. Suture slightly channeled. Umbilicus very narrow, partially covered by an extension of the columellar margin. Aperture narrow, wider anteriorly, and long, about 9/10 of the body whorl length. Columellar margin thickened, slightly oblique, with a small, simple fold. Sculpture of a number of punctuated spiral grooves. The punctuations are conspicuous, oval, and partially fused to the next one within each groove. The grooves are separated by gaps that are about as wide as the grooves themselves. Colour uniformly cream.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — “ Acteon ” sp. 10 is very similar to Maxacteon fabreanus (Crosse, 1874) in shell morphology, but is clearly distinguishable from this species in having much larger punctuations in the spiral grooves and the grooves separated by wider gaps (see Hori 2000a).

Since there is only one specimen of “ Acteon ” sp. 10 it is not possible to determine whether this is a juvenile of another species of Acteonidae , so it is not named here.

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