Cylichna biplicata (A. Adams in Sowerby, 1850)

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 652-656

Cylichna biplicata (A. Adams in Sowerby, 1850)

Figs 30A-C, 31A, B, 32A, 33

Bulla strigella A. Adams in Sowerby, 1850 [in 1848-50]: 592, pl. 125, fig. 141 [non Bulla strigella Lovén, 1846 – Family Retusidae ]. Bulla biplicata A. Adams in Sowerby, 1850 [in 1848-50]: 593, pl. 125, fig. 143.

Synonyms:

Cylichna javanica Schepman, 1913: 471 , pl. 32, fig. 6.

Cylichna sundaica Thiele, 1925: 317 , pl. 32, figs 14-14a.

Cylichna braunsi Yokoyama, 1920: 28 , pl. 1, fig. 5.

Cylichna authuri Dautzenberg, 1929: 230 [Replacement name for Bulla strigella A. Adams].

Cylichna koryusyoensis Nomura, 1935: 96 , pl. 6, figs 4a-b.

TYPE MATERIAL. — B. strigella (not examined). — C. biplicata : possible syntype BMNH 1996428 . — C. javanica : probably lost (could not be located at ZMA). — C. sundaica : probably lost (could not be located at MNHB). — C. braunsi (not examined). — C. koryusyoensis (not examined).

TYPE LOCALITY. — B. strigella : Cagayan, Philippines, 45.7 m. — C. biplicata : China Seas. — C. javanica: Djangkar, Jawa , Indonesia, 9 m [ Siboga : stn 4]. — C. sundaica: Padang , Sumatra [ Valdivia ]. — C. braunsi: Naganuma , Totsuka-ku, Yokohama City, Japan (Pleistocene). — C. koryusyoensis : Taiwan (Pliocene).

MATERIAL EXAMINED. — Philippines. MUSORSTOM 3: stn CP 20°57’S, 165°35’E, 160-222 m, 3 dd; stn DW 706 , Passe SE de 101, 14°00’N, 120°19’E, 194-196 m, 1 dd; stn DR 140, 11°43’N, Ngoe, 21°42’S, 166°34’E, 247-252 m, 1 dd .

122°34’E, 93-99 m,>100 dd. Vanuatu. MUSORSTOM 8: stn CP 1131-1132, 15°38’S, 167°03- North of New Caledonia.MUSORSTOM 4:stn DW 149, 19°08’S, 04’E, 140-182 m, 1 dd.

163°23’E, 155 m, 6 dd; stn DW 150 , 19°07’S, 163°22’E, 110 m, Fiji. MUSORSTOM 10: stn CP 1323, Bligh Water, 17°16’S, 4 dd (Fig. 30A); stn DW 151 , 19°07’S, 163°22’E, 200 m, 1 dd. 177°46’E, 143-173 m, 1 dd; stn DW 1329 , Bligh Water , 17°19’S, New Caledonia proper. LAGON: stn 830, Secteur de Poindimié, 177°47’E, 102-106 m, 6 dd; stn CP 1363, S of Viti Levu, 18°12’S, 20°49’S, 165°19’E, 105-110 m, 1 dd . — BATHUS 1 : stn DW 677 , 178°33’E, 144-150 m, 1 dd . — BORDAU 1 : stn DW 1435 , 17°11’S, Grande Passe de Touho , 20°49’S, 165°19’E, 96-109 m, 2 lv, dis- 178°45’W, 170-183 m, 1 dd .

sected (Figs 30B, C, 31A, B, 32A); stn DE 700, Passe du Cap Baye,

FIG. 30. Shell morphology of species of Cylichna Lovén,1846 . A-C, Cylichna biplicata (A. Adams in Sowerby, 1850). A, (10 mm), ventral view, New Caledonia, MUSORSTOM 4 stn DW 150; B, (9 mm), ventral view, New Caledonia, BATHUS 1 stn DW 677; C, same shell, posterior view. D, E, Cylichna sibogae Schepman, 1913 . D, (12 mm), ventral view, Philippines, MUSORSTOM 2 stn DR 34; E, same shell, posterior view. F, G, Cylichna involuta (A. Adams in Sowerby, 1850). F, (9 mm), ventral view, New Caledonia, BATHUS 1 stn DW 687; G, same shell, posterior view. H-J, Cylichna cf. protracta Gould, 1859 . H, juvenile shell, (6 mm), ventral view, Tonga, BORDAU 2 stn DW 1531; I, adult shell, (16 mm), ventral view, Tonga, BORDAU 2 stn DW 1531; J, same shell, posterior view.

FIG. 31. Gizzard plates and radulae of species of Cylichna Lovén, 1846 . A, B, Cylichna biplicata (A. Adams in Sowerby, 1850). A, radula, New Caledonia, BATHUS 1 stn DW 677, scale bar = 30 Μm; B, same specimen, gizzard plate, scale bar = 100 Μm. C, D, Cylichna involuta (A. Adams in Sowerby, 1850). C, radula, Coral Sea, MUSORSTOM 5 stn 298, scale bar = 30 Μm; D, same specimen, gizzard plate, scale bar = 200 Μm. E, F, Cylichna consobrinoides Kuroda & Habe, 1952 . E, radula, Coral Sea, MUSORSTOM 5 stn 380, scale bar = 100 Μm; F, same specimen, gizzard plate, scale bar = 500 Μm.

DISTRIBUTION. — Originally described from the China Sea. Reported subsequently from the Philippines, Japan, Indonesia and Madagascar under several names (see Remarks below). Material herein from Fiji, New Caledonia, the Philippines and Vanuatu (Fig. 33), in 99-247 m, live in 96-109 m.

DESCRIPTION. — Shell morphology. Length 18 mm, width 6 mm (largest specimen examined). Shell solid, elongate, with nearly parallel sides (Figs 30A, B). Only 1 whorl visible, forming nearly the entire shell. Apex rounded, deeply umbilicate (Fig. 30C), with the aperture lip rising from the centre. 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 conspicuously thickened. Columella with one fold (Fig. 30B), in some specimens medially grooved (Fig. 30A). Small umbilicus, covered by the columellar fold in some specimens. Sculpture of a number of irregular spiral lines more conspicuous near the anterior and posterior ends of the shell. Colour dirty white, but covered with pale grey or yellowish periostracum, with reddish brown areas near the anterior and posterior ends of the shell. The spiral lines near the anterior and posterior borders of the shell are dark reddish brown. The apex and the columella are opaque white.

Anatomy. The digestive system contains 3 smooth gizzard plates similar in shape and size. All the plates are oval and elongate (Fig. 31B). The radular formula is 16 x 3.1.1.1. 3 in a specimen from New Caledonia (BATHUS 1 stn DW 677). The rachidian teeth are broad with a number of sharp denticles decreasing in size towards the laterals of each plate (Fig. 31A). There is a gap with no denticles on the centre of each rachidian tooth. The innermost lateral teeth are hook-shaped, with a long, strong cusp with 10-15 denticles. The 3 outermost teeth of each row are much smaller, but also hook-shaped with a long, thin cusp and several small denticles.

The reproductive system is monoaulic (Fig. 32A). The ampulla is long and convoluted. It connects to a short and wide post-ampullary duct. The seminal receptacle enters the post-ampullary duct that 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 short and straight.

material of C. javanica and C. sundaica is probably lost; it could not be located at the ZMA and MNHB, respectively, but the original descriptions are detailed enough to allow a positive identification of these species and to recognize them as additional synonyms.

Cylichna braunsi Yokoyama, 1920 , reported from Japan and the Philippines and illustrated by Hori (2000b), and Cylichna koryusyoensis Nomura 1935 , described from the Pliocene of Taiwan, are also very similar to C. biplicata and here regarded as synonyms.

Cylichna authuri Dautzenberg 1929 is a replacement name for Bulla strigella A. Adams in Sowerby, 1850.