Relichna sumatrana (Thiele, 1925)

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 762-764

Relichna sumatrana (Thiele, 1925)

Figs 84E-I, 85C, 86A, 89

Cylichna sumatrana Thiele, 1925: 276 , pl. 32, fig. 8.

TYPE MATERIAL . — Lost (could not be located at MNHB).

TYPE LOCALITY. — Siberut Island , southwest of Sumatra, Indonesia, 0°39.2’S, 98°52.3’W, 750 m [ Valdivia : stn 191] .

MATERIAL EXAMINED. — New Caledonia proper. BATHUS 800 m, 3 dd ( Figs 84E, F); stn DE 682, Grande Passe de Touho, 1: stn CP 660, Passe du Cap Baye, 21°11’S, 165°53’E, 786- 20°47’S, 165°21’E, 491-500 m, 1 dd . — Large Hienghène , 200 m, 6 September 1978, 1 dd. 660-663 m, 1 dd . — BORDAU 1 : stn CP 1413, 16°10’S, 179°24’W ,

Loyalty Ridge. BIOCAL: stn DW 106 , 21°36’S, 166°29’E, 625- 669- 676 m, 2 dd; stn DW 1459 , 17°18’S, 179°33’W, 820-863 m, 650 m, 7 dd; stn CP 232, 21°34’S, 166°27’E, 760-790 m, 11 dd, 38 dd; stn DW 1485 , 19°03’S, 178°30’W, 700-707 m, 65 dd; stn 2 lv . — BIOCAL: stn DW 80 , 20°32’S, 166°48’E, 900-980 m, 1 dd. DW 1486 , 19°01’S, 178°26’W, 395-540 m, 1 dd; stn DW 1488 , — BIOGEOCAL: stn CP 232, 21°34’S, 166°27’E, 760-790 m, 1 lv 19°01’S, 178°25’W, 500-516 m, 1 dd; stn CP 1490, 18°51’S, (Figs 85C, 86A); stn DW 289 , 20°36’S, 167°00’E, 830-840 m, 2 178°32’W, 785-820 m, 1 dd .

dd. — MUSORSTOM 6: stn CP 438, 20°23’S, 166°20’E, 780 m, 1 Wallis and Futuna. MUSORSTOM 7: stn DW 539 , Banc Combe, dd; stn DW 488 , 20°49’S, 167°06’E, 800 m, 1 dd; stn DW 489 , 12°27’S, 177°27’W, 700 m, 1 dd; stn DW 576 , Banc Waterwitch, 20°48’S, 167°06’E, 700 m, 1 dd . — BATHUS 3 : stn DW 786 , Mont 12°31’S, 176°53’W, 680-685 m, 1 dd; stn DW 578 , Wallis Island, J, 23°54’S, 169°49’E, 699-715 m, 1 dd. 13°08’S, 176°16’W, 640-730 m, 1 dd .

Vanuatu. MUSORSTOM 8: stn CP 991, 18°51’S, 168°52’E, 910- Tonga. BORDAU 2: stn DW 1531, Eua, 21°12’S, 174°56’W, 936 m, 1 dd; stn CP 992, 18°52’S, 168°55’E, 748-775 m, 2 dd; 970-983 m, 3 dd; stn DW 1553, S of Nomuka Islands, 20°42’S, stn CP 993, 18°49’S, 168°54’E, 780-783 m, 1 dd; stn CC 1034, 174°54’W, 650-676, 27 dd (Figs 84G-I); stn CP 1565, NW of Ton- 17°55’S, 168°42’E, 690-750 m, 1 dd; stn DW 1063, 16°16’S, gatapu, 20°58’S, 175°16’W, 869-880 m, 2 dd; stn DW 1588, Va- 167°18’E, 650-719 m, 1 dd; stn CP 1082, 15°53’S, 167°20’E, 465- va‘u Islands, 18°40’S, 173°52’W, 630-710 m, 15 dd; stn DW 1599, 550 m, 1 dd; stn DW 1113, 14°53’S, 167°06’E, 700-736 m, 2 dd; centre of Ha‘apai Islands, 20°44’S, 174°52’W, 720-760 m, 1 dd; stn DW 1128, 16°02’S, 166°38’E, 778-811 m, 4 dd. stn DW 1601, 20°50’S, 174°57’W, 200-487 m, 1 dd; stn CP 1625,

Fiji. MUSORSTOM 10: stn DW 1314, Bligh Water, 17°16’S, Seamount, 23°28’S, 176°22’W, 824 m, 3 dd.

178°15’E, 656-660 m, 2 dd; stn DW 1345, 17°15’S, 178°30’E,

DISTRIBUTION. — Originally described from Indonesia, in 750 m. Material herein collected from Fiji, New Caledonia, Tonga, Vanuatu and the Wallis and Futuna region (Fig. 89), in 200-970 m, live in 760-790 m.

FIG. 89. Collection localities of species of Relichna Rudman, 1971 in the southwest Pacific: °, Relichna pachys (Watson, 1883) . Z, Relichna truncatula (Schepman, 1913) . •, Relichna sumatrana (Thiele, 1925) .

DESCRIPTION. — Shell morphology. Length 17 mm, width 6 mm (largest specimen examined). Shell solid, elongate, with nearly parallel sides in larger specimens (c. 10 mm or longer; Figs 84E, I) and oval with convex sides in smaller specimens (less than 10 mm long; Figs 84G, H). Some specimens are much wider in the central region of the shell, narrowing towards the posterior end (Fig. 84I), whereas others are almost the same width along the entire shell (Fig. 84E). Only 1 whorl visible, except for a small visible portion of the top of the spire. Apex truncate to oval, deeply umbilicate (Fig. 84F). Anterior end of the shell rounded. Aperture as long as the shell, wider anteriorly and narrowing gradually at about 1/5 of its length. Columellar margin thickened. Columella with 1 inconspicuous fold in some specimens, absent in other specimens. There are transitional forms between these two morphologies. Umbilicus closed. Sculpture of faint growth lines. Colour uniformly dirty white.

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

The reproductive system is monaulic (Fig. 86A). The ampulla is very long and convoluted. It connects to the short and wide post-ampullary duct. The seminal receptacle enters the post-ampullary duct, which continues distally to the common general atrium. The bursa copulatrix also enters the common atrium. From the gonopore an open seminal groove runs anteriorly to the protrusible cephalic penis and the prostate. The prostate is elongate. There is a short ejaculatory duct. A spermatic bulb has not been found.

REMARKS. — Cylichna sumatrana was originally described based on several shells collected from Siberut Island, southwest of Sumatra, Indonesia (Thiele 1925). Unfortunately the type material is lost; it could not be located at the MNHB. The material here examined matches the original description of C. sumatrana in having an elongate, smoothlooking shell with a narrow, deeply umbilicate apex.

This species is here transferred to the genus Relichna because of the absence of a radula and jaws and presence of 3 unequal and smooth gizzard plates.