Cylichna cf. protracta Gould, 1859

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 657-658

publication ID	978-2-85653-614-8
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scientific name	Cylichna cf. protracta Gould, 1859
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Cylichna cf. protracta Gould, 1859 View in CoL

Figs 30H, J, 33

Cylichna protracta Gould, 1859: 140 View in CoL .

TYPE MATERIAL. — Holotype USNM 1864 About USNM (not examined).

TYPE LOCALITY. — China .

MATERIAL EXAMINED. — Coral Sea. MUSORSTOM 5: stn 358, Fiji. MUSORSTOM 10: stn DW 1388 , S of Viti Levu, 18°19’S, Chesterfield Islands , 19°39’S, 158°47’E, 680-700 m, 1 dd. 178°02’E, 313-446 m, 1 dd GoogleMaps . — BORDAU 1 : stn DW 1408 , North of New Caledonia. BATHUS 4 : stn DW 914 , Grand Pas- 16°02’S, 179°30’W, 550-561 m, 1 dd; stn DW 1432 , 17°20’S, sage, 18°49’S, 163°15’E, 600-616 m, 2 dd; stn DW 917 , 18°47’S, 178°44’W, 477-493 m, 1 dd, stn DW 1488 , 19°01’S, 178°25’W, 163°14’E, 397-400 m, 1 dd. 500-516 m, 1 dd GoogleMaps .

New Caledonia proper. BIOCAL: stn DW 33, 23°10’S, Wallis and Futuna. MUSORSTOM 7: stn DW 507, Futuna Is- 167°10’E, 675-680 m, 2 lv, 1 destroyed to dissect the gizzard land, 14°20’S, 178°07’W, 419-425 m, 1 dd; stn DW 523, Wallis plates; stn DW 48, 23°00’S, 167°29’E, 775 m, 4 dd. Island, 13°12’S, 176°16’W, 455-515 m, 2 dd; stn DW 585, Wal- Norkfolk Ridge. BATHUS 3: stn DW 807, Banc Jumeau Ouest, lis Island, 13°10’S, 176°13’W, 415-475 m, 1 dd.

23°40’S, 167°59’E, 420-438 m, 1 dd; stn DW 809 , 23°39’S, Tonga. BORDAU 2 : stn DW 1509 , Tongatapu, 21°05’S, 175°22’W, 167°59’E, 650-730 m, 1 dd GoogleMaps . — SMIB 8 : stn DW 146-147 , Mont B, 456-510 m, 3 dd; stn DW 1531 , Eua, 21°12’S, 174°56’W, 970-983 Banc Eponge, 24°55’S, 168°22’E, 508-532 m 2 dd. m, 2 dd (Figs 30H-J); stn DW 1544 , SW of Tongatapu, 21°18’S, Loyalty Ridge. BATHUS 3 : stn DW 790 , Mont J, 23°49’S, 175°18’W, 441-443 m, 1 dd; stn DW 1549 , S of Nomuka Islands, 169°48’E, 685-715 m, 1 dd. 20°38’S, 175°00’W, 500 m, 1 dd; stn DW 1555 , Channel N of Vanuatu. MUSORSTOM 8: stn DW 972 , 19°22’S, 169°28’E, Nomuka, 20°11’S, 174°45’W, 591 m, 1 dd; stn DW 1597 , centre 487-507 m, 1 dd. of Ha‘apai Islands , 20°40’S, 174°55’W, 598-610 m, 3 dd GoogleMaps .

DISTRIBUTION. — Originally described from China. Material herein collected from several localities in New Caledonia, Tonga and Futuna (Fig. 33), in 346-970 m, live in 675-680 m.

FIG. 33. Collection localities of species of Cylichna Lovén, 1846 in the southwest Pacific: °, Cylichna biplicata (A. Adams in Sowerby, 1850). Z, Cylichna involuta (A. Adams in Sowerby, 1850). •, Cylichna cf. protracta Gould, 1859 .

DESCRIPTION. — Shell morphology. Length 17 mm, width 6 mm (largest specimen examined). Shell solid, elongate, with nearly parallel sides (Figs 30H-I). Only 1 whorl visible, forming the entire shell. Apex not umbilicate (Fig. 30J), truncate in larger specimens (more than 10 mm long; Fig. 30I), or rounded in smaller specimens (less than 10 mm long; Fig. 30H). 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 no folds. Umbilicus closed. Sculpture only faint growth lines. Colour uniform dirty white to light brown.

Anatomy. The digestive system contains 3 smooth gizzard plates similar in shape and size. All the plates are oval and elongate. Radula and reproductive system unknown.

REMARKS. — Cylichna protracta was originally described from China as a solid, elongate species with an obliquely truncate apex and an apical perforation (Gould 1959). Recently Higo et al. (2001) illustrated the holotype, which is very similar to the material here examined. The only differences found are that the shell of the holotype is more elongate and has an apical perforation, being an adult shell. In the material from the southwest Pacific only immature specimens have apical perforations and it is here provisionally assigned to C. protracta until more comparative material becomes available.

Cylichna protracta is assigned to the genus Cylichna based on the presence of 3 smooth and oval gizzard plates and an elongate shell. Unfortunately the radula of the single specimen with soft parts was destroyed during the dissection process and its morphology is unknown. Therefore the generic placement of this species is tentative.