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 : 640-641

“ Acteon ” sp. 11

Figs 24C, 25

MATERIAL EXAMINED. — Fiji. SUVA 2: stn BS 26, Viti Levu south Lagoon, 18°09’S, 178°30’E, 113 m, 1 dd (Fig. 24C) .

Tonga. BORDAU 2: stn DW 1585, Vava’u Islands, 18°33’S, 173°57’W, 578 m, 2 dd.

DISTRIBUTION. — Collected from Fiji and Tonga (Fig. 25), in 113-578 m.

DESCRIPTION. — Shell morphology. Length 6 mm, width 2.5 mm (smallest specimen examined; spire eroded in the largest specimen). Shell solid, very elongate, with convex sides (Fig. 24C). Body whorl large, from 2/3 to 3/4 of the shell length. Spire long, conical, with 3 long whorls. Suture slightly channeled. Umbilicus closed. Aperture long, about 2/3 of the body whorl length, wide anteriorly, narrowing abruptly at about 1/2 its 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 become wider towards the posterior end of the spire. Near the posterior end of the spire there is a wide area with no grooves, followed by 2 grooves close to each other and having large puctuations. Between the last groove and the suture there is another area with no grooves in the smallest specimen. In the largest specimen the last groove is very close to the suture. Colour pale orange-reddish with a colourless band on the edge of the spire. Interior of the aperture with an orange tinge.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — “ Acteon ” sp. 11 is very similar to Acteon chrystomatus n. sp. in sculpture morphology and colouration. However, they are easily distinguishable by the shell profile that is much more elongated and with a narrower aperture in A. chrystomatus . “ Acteon ” sp. 11 is clearly distinguishable from other species here described and is probably an unnamed species. Because of the lack of enough material “ Acteon ” sp. 11 is not here described. There are some minor morphological differences in the sculpture of the two specimens examined, but again because of the lack of enough material they are provisionally maintained in the same species.

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