Retusa sp. 1

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 740

Retusa sp. 1

Figs 75G, H, 78

MATERIAL EXAMINED. — Fiji. BORDAU 1 : stn DW 1459 , 17°18’S, 179°33’W, 820-863 m, 1 dd .

DISTRIBUTION. — Single specimen collected from Fiji (Fig. 78), in 820-863 m.

DESCRIPTION. — Shell morphology. Length 4.5 mm, width 2.5 mm (single specimen examined). Shell fragile, elongate, wider anteriorly and narrower posteriorly, with a convex right side and slightly concave left side (Fig. 75G). Only 1 whorl visible, forming nearly the entire shell with the exception of a visible portion of the spire. Protoconch partially visible. Apex deeply umbilicate (Fig. 75H), with the aperture lip slightly rising from the right side. The aperture lip forms a rounded wing connected to the columellar margin. Anterior end of the shell rounded. Aperture as long as the shell, wider anteriorly and narrowing gradually at about 1/3 of its length. Columellar margin slightly thickened. Columella simple, with no folds. Umbilicus closed. Sculpture of a number of faint growth lines. Colour uniformly dirty white.

Anatomy. Unknown. The single shell collected lacked soft parts.

REMARKS. — Retusa sp. 1 is similar to Retusa sakuraii (Habe, 1958) , originally described from Japan, and illustrated by Hori (2000c). Both species share a pyriform shell, wider anteriorly with a deep apical umbilicus and a smooth, dirty white shell. Differences between them include the more elongate shape of the apical wing of R. sakuraii . Retusa sp. 1 may belong to R. sakuraii but examination of additional material is necessary to confirm this.

This species is placed in the genus Retusa , pending availability of complete specimens.