Cylichna sp. 2

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 664-665

Cylichna sp. 2

Figs 36, 37C, D

MATERIAL EXAMINED. — Loyalty Ridge. BIOGEOCAL: stn CP 260, 21°00’S, 166°58’E, 1820-1980 m, 1 dd.

DISTRIBUTION. — Single specimen collected from New Caledonia (Fig. 36), in 1820-1980 m .

FIG. 36. Collection localities of species of Cylichna Lovén, 1846 in the southwest Pacific: °, Cylichna grovesi n. sp. Z, Cylichna sp. 1 . •, Cylichna sp. 2 . σ, Cylichna sp. 3 . ◇, Cylichna sp. 4 .

DESCRIPTION. — Shell morphology. Length 2 mm, width 0.8 mm (largest specimen examined). Shell fragile, oval, narrow anteriorly, with slightly convex sides (Fig. 37C). Only 1 whorl visible, forming nearly the entire shell, except for a small visible portion of the spire. Apex truncate, slightly depressed, partially covered by the columellar margin (Fig. 37D), with the aperture lip not rising from the left side. Protoconch visible. Anterior end of the shell elongate. Aperture as long as the shell, wider anteriorly and narrowing gradually at about 1/3 of its length. Columellar margin thickened. Columella smooth with no folds. Umbilicus long and deep. Sculpture of faint growth lines. On the posterior end of the spire there is a distinctive pattern of curved and well-marked growth lines. Colour uniformly dirty white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — Cylichna sp. 2 resembles Cylichna tanyumphalos n. sp. in shell morphology. These two species share a deep and long umbilicus and an elongate anterior end of the shell. However, Cylichna sp. 2 is a much shorter species with a truncate apex.

This species is provisionally assigned to the genus Cylichna because of the resemblance of its shell morphology to that of other members of the genus, pending complete specimens becoming available for study.