Cylichna sp. 4

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 667

Cylichna sp. 4

Figs 36, 37G, H

MATERIAL EXAMINED. — Loyalty Ridge. BATHUS 3 : stn DW 800 , Mont D, 23°35’S, 169°37’E, 655 m, 1 dd .

DISTRIBUTION. — Single specimen herein collected from New Caledonia (Fig. 36), in 655 m.

DESCRIPTION. — Shell morphology. Length 1.5 mm, width 0.8 mm (single specimen examined). Shell fragile, oval, with slightly convex sides (Fig. 37G). Only 1 whorl visible, forming nearly the entire shell. Apex rounded, concave (Fig. 37H), with the aperture lip rising slightly from the left side, and forming a short wing connected to the columellar margin. Protoconch partially visible. Anterior end of the shell rounded. Aperture as long as the shell, wider anteriorly, narrowing abruptly at about 1/3 of its length and widening again near 2/3 of its length. Columellar margin slightly thickened. Columella smooth, with no folds. Umbilicus narrow, partially covered by an expansion of the columellar margin. Sculpture of a number of faint growth lines. There are 4 simple spiral grooves near the anterior end of the shell. Colour uniformly shiny white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — Cylichna sp. 4 appears distinct from other species of the genus. The most distinctive feature is the shape of the aperture, which is narrower in the central part of the shell and wider near both the anterior and posterior ends. Considering the small size of the single specimen collected it is possible that Cylichna sp. 4 is a juvenile of another species, but it is provisionally maintained as distinct until more material becomes available.

The shell of Cylichna sp. 4 resembles that of other species of Cylichna and therefore it is provisionally placed in this genus.