Relichna hadra, 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 : 764-765

Relichna hadra n. sp.

Figs 84C, D, 85B, 86B, 90

TYPE MATERIAL. — Holotype MNHN 20398 and 6 paratypes MNHN 20399-20404, 1 paratype LACM 3008 .

TYPE LOCALITY . — Norfolk Ridge , 24°55’S, 168°22’E, 513 m [ SMIB 3 : stn DW 3 ] .

MATERIAL EXAMINED. — Norfolk Ridge. BIOCAL: stn DW 51 , stn DW 3 , 24°55’S, 168°22’E, 513 m, 2 dd, holotype (MNHN 23°05’S, 167°45’E, 680-700 m, 1 dd, paratype (MNHN 20400); 20398; Figs 84C, D) and paratype (MNHN 20399) . — SMIB 8 : stn DW 53 , 23°09’S, 167°43’E, 975-1005 m, 1 dd, paratype stn DW 149 , Mont B, Banc Eponge, 24°55’S, 168°22’E, 508- (MNHN 20401); stn DW 66 , 24°55’S, 168°22’E, 505-515 m, 1 510 m, 1 dd, paratype (MNHN 20404); stn DW 152 , 24°54’S, dd, paratype (MNHN 20402); stn DW 70 , 23°25’S, 167°53’E, 168°22’E, 514-530 m, 1 dd, paratype ( LACM 3008 ) .

965 m, 1 lv, paratype (MNHN 20403; Figs 85B, 86B) . — SMIB 3 :

DISTRIBUTION. — Collected from New Caledonia (Fig. 90), in 510-975 m, live in 965 m.

DESCRIPTION. — Shell morphology. Length 11 mm, width 6 mm (largest specimen examined). Shell solid, short, and oval, with a right concave side and a left convex side (Fig 84C). Only 1 whorl visible, forming nearly the entire shell, except for a small visible portion of the top of the spire. Apex flat, umbilicate (Fig. 84D). Aperture lip rising from the left 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 1/2 of its length. Columellar margin slightly thickened. Columella with 1 small fold. Umbilicus narrow, partially covered by a columellar extension. Sculpture of a number of inconspicuous growth lines. Colour uniformly dirty white.

Anatomy. The digestive system contains 3 smooth, unequal gizzard plates (Fig. 85B). There is no radula.

The reproductive system contains a complex ejaculatory duct connected to a spermatic bulb and the prostate (Fig. 86B). The female and hermaphroditic organs are unknown.

REMARKS. — This species is assigned to the genus Relichna because of the absence of radula and jaws and the presence of 3 smooth and unequal gizzard plates.

Relichna hadra is clearly distinguishable from other species of Relichna here reviewed by the twisted shape of the shell with a right concave side and a left convex side. Also, the reproductive anatomy is clearly distinct, with a complex ejaculatory duct connected to a spermatic bulb and the prostate. Relichna murdochi Suter, 1913 , the type species of the genus, also has a spermatic bulb (Rudman 1971), but the ejaculatory duct is short and simple.

ETYMOLOGY. — From the Greek adjective hadros (thick, bulky, strong), in reference to the thick and large shell of this species.