Relichna 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 : 765

Relichna sp. 1

Figs 88E, F, 90

MATERIAL EXAMINED. — North of New Caledonia. BATHUS 4 : stn DW 914 , 18°49’S, 163°15’E, 600-616 m, 12 dd .

Norfolk Ridge. BIOCAL:stn DW 33, 23°10’S, 167°10’E, 675-680

m, 4 dd; stn DW 48, 23°00’S, 167°29’E, 775 m, 2 dd; stn DW 49, 23°03’S, 167°32’E, 825-830 m, 2 dd; stn DW 53, 23°09’S, 167°43’E, 975-1005 m, 10 dd (Figs 88E, F).

DISTRIBUTION. — Collected from New Caledonia (Fig. 90), in 616-975 m.

DESCRIPTION. — Shell morphology. Length 8 mm, width 5 mm (largest specimen examined). Shell solid, short and oval, with a right concave side and a left convex side in some specimens (Fig 88E) or both sides convex in other specimens. Only 1 whorl visible, forming nearly the entire shell, except for a small visible portion of the top of the spire in some specimens. Apex rounded, not umbilicate in most specimens and with a shallow and narrow umbilicus in some other specimens (Fig. 88F). The aperture lip ends slightly below the posterior end of the shell, and is 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 with 1 small fold. Umbilicus closed. Sculpture of a number of inconspicuous growth lines. Colour uniformly dirty white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — The anatomy of this species is unknown so it is here assigned to the genus Relichna on the basis of its conchological similarities to other species of the genus here reviewed, pending the availability of anatomical information.

Relichna sp. 1 is not named here because of the absence of anatomical information, but it appears to be a distinct species. It is distinguished from other members of the genus by lacking an apical umbilicus or having a shallow and reduced apical umbilicus. Another consistent distinguishing feature is the shape of the aperture lip, which ends slightly below the posterior end of the shell.