Philine abyssicola, Valdés, 2008

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 723

Philine abyssicola n. sp.

Figs 64F-G, 68

TYPE MATERIAL. — Holotype MNHN 20389 and 2 paratypes MNHN 20390.

TYPE LOCALITY. — Southeast of Viti Levu, Fiji, 18°00.0’S, 178°53.7’E, 1058-1091 m [MUSORSTOM 10: stn CP 1361] .

MATERIAL EXAMINED. — Fiji. MUSORSTOM 10: stn CP 1361, SE of Viti Levu , 18°00’S, 178°54’E, 1058-1091 m, 3 lv, holotype

and paratypes.

DISTRIBUTION. — Known only from Fiji (Fig. 68), in 1058-1091 m .

DESCRIPTION. — Shell morphology. Length 4 mm, width 5 mm (holotype). Shell fragile, oval, with the right side convex and the left side posteriorly concave and anteriorly convex (Fig. 64F). The widest region of the shell is near the anterior end. Body whorl very large; spire short, with 1 whorl. Anterior end of the shell rounded. Umbilicus closed. Aperture almost as long as the shell, wide anteriorly, narrowing at about 3/4 of its length. Aperture lip not rising. Columellar margin slightly thickened near the anterior end. Sculpture of a number of punctuated spiral grooves. The punctuations are large, oval to elongate, and separated from the next ones within each groove. The grooves are separated by gaps about as wide as the grooves themselves, and occasionally narrower grooves are intercalated. Colour uniformly dirty white.

Anatomy. The gizzard plates have not been examined. The radular formula is 13 x 2.1.0.1. 2 in the holotype (MUSORSTOM 10 stn CP 1361). The inner lateral teeth are triangular, with a wide base and a short, strong, curved cusp devoid of denticles (Fig. 64G). The outer lateral teeth are hook-shaped and thin.

REMARKS. — The external morphology and reproductive system of this species are unknown, but the shell and radula morphology are distinctive enough to justify description of a new species. The shell of P. abyssicola is large and probably occupies a large portion of the posterior shield. It resembles the shell of P. cumingii , but it is shorter and wider. Other differences between these species are in the radula, which has triangular innermost teeth in both species, but they are denticulate in P. cumingii and smooth in P. abyssicola .

There are no other Indo-Pacific species of Philine with similar shell morphology. Description of species of Philine without information on the reproductive system morphology is not ideal, but this species is very uncommon and occurs in very deep waters, and it is unlikely that complete specimens will become available for study anytime soon.

ETYMOLOGY. — From the Ancient Greek abyssos (deep) and the Latin cola (dweller), in reference to the habitat of this species, used as a noun in apposition.