Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific Author Valdés, Ángel John T. Huber text Mémoires du Muséum national d'Histoire naturelle 2008 196 587 792 journal article 978-2-85653-614-8 1243-4442 Cylichna involuta (A. Adams in Sowerby, 1850) Figs 30F, G, 31C, D, 32B, 33 Bulla involuta A. Adams in Sowerby, 1850 [ in 1848-50]: 595, pl. 125, fig. 151. TYPE MATERIAL . — Not examined . TYPE LOCALITY . — China Seas . MATERIAL EXAMINED. — Indonesia . KARUBAR: stn DW 29 , de Ngoe , 21°42’S , 166°34’E , 247-252 m , 1 dd . — BATHUS 4 : stn Kai Islands , 05°36’S , 132°56’E , 181-184 m , 8 dd; stn DW 32 , DW 887 , Passe de Duroc , 21°07’S , 164°28’E , 320-344 m , 2 dd. 05°47’S , 132°51’E , 170-206 m , 1 dd; stn DW 49 , Tanimbar Is- Norfolk Ridge . SMIB 8 : stn DW 159 , Banc Kaimon-Maru, lands, 08°00’S , 132°59’E , 206-210 m , 9 dd; stn DW 50 , 07°59’S , 24°46’S , 168°08’E , 241-245 m , 1 dd . 133°02’E , 184-186 m , 2 dd. Loyalty Ridge . MUSORSTOM 6: stn DW 406, 20°41’S , 167°07’E , Coral Sea . MUSORSTOM 5: stn 298, Banc Argo, 22°44’S , 373 m , 1 dd; stn DW 459, 21°01’S , 167°31’E , 425 m , 1 dd. 159°22’E , 320 m , 1 lv , dissected (Figs 31C, D, 32B). Vanuatu . MUSORSTOM 8: stn DW 976, 19°25’S , 169°27’E , North of New Caledonia . BATHUS 4: stn DW 901, Grand Pas- 160-182 m , 1 dd. sage, 19°03’S , 163°15’E , 297 m , 1 dd. Fiji . BORDAU 1 stn DW 1410 , 16°06’S , 179°28’W , 400-410 m , New Caledonia proper . VAUBAN : stn 2, 22°17’S , 167°14’E , 1 dd; stn DW 1416 , 16°30’S , 178°59’W , 441-450 m , 1 dd; stn 425-430 m , 1 dd; stn 3, 22°17’S , 167°12’E , 390 m , 3 dd . — BIO- DW 1464 , 18°09’S , 178°38’W , 285-300 m , 1 dd; stn DW 1469 , CAL: stn DW 41 , 22°45’S , 167°12’E , 380-410 m , 1 dd; stn DW 19°40’S , 178°10’W , 314-377 m , 2 dd . 77, 22°15’S , 167°15’E , 440 m , 5 dd. — BATHUS 1 : stn DW 683 , Tonga . BORDAU 2 : stn DW 1552 , S of Nomuka Islands , 20°38’S , Passe de Hienghu , 20°35’S , 165°07’E , 380-400 m , 7 dd; stn DW 174°58’W , 491-500 m , 1 dd; stn DW 1587 , Vava‘u Islands, 687, 20°35’S , 165°07’E , 408-440 m , 21 dd & lv, 1 of them des- 18°37’S , 173°54’W , 309-400 m , 2 dd; stn DW 1601 , centre of troyed to dissect the radula (Figs 30F, G); stn DW 706 , Passe SE Ha‘apai Islands , 20°50’S , 174°57’W , 200-487 m , 2 dd . DISTRIBUTION . — Reported from the China Seas and Japan , in 66-95 m (Hori 2000b). Included herein are the first records from the Coral Sea , Fiji, Indonesia, New Caledonia, Tonga and Vanuatu (Fig. 33), in 182-491 m , live in 320-408 m . DESCRIPTION. — Shell morphology . Length 9 mm , width 3.5 mm (largest specimen examined). Shell solid, elongate, with nearly parallel sides (Fig. 30F). Only 1 whorl visible, forming nearly the entire shell. Apex flat, slightly rounded in some specimens, with a deep and narrow umbilicus (Fig. 30G). The aperture lip rises from the left side and forms a short wing that connects to the columellar margin. Anterior end of the shell rounded. Aperture as long as the shell, wider anteriorly and narrowing abruptly at about 1/5 of its length. Columellar margin thickened. Columella with one inconspicuous fold. Umbilicus narrow and deep. Sculpture of a number of irregular spiral grooves crossed by faint growth lines. Colour uniformly shiny white. Anatomy . The digestive system contains 3 smooth gizzard plates similar in shape and size. All the plates are oval and elongate (Fig. 31D). The radular formula is 13 x 5.1.1.1. 5 in a specimen from the Coral Sea (MUSORSTOM 5 stn 298) and 16 x 5.1.1.1. 5 in a specimen from New Caledonia (BATHUS 1 stn DW 687). The rachidian teeth are broad, with a number of sharp denticles decreasing in size towards the laterals of each plate (Fig. 31C). There is a gap with no denticles on the centre of each rachidian tooth. The innermost lateral teeth are hook-shaped, with a long and strong cusp with 10-15 denticles. The 5 outermost teeth of each row are much smaller, but also hook-shaped with a long, thin cusp and numerous small denticles. The reproductive system is monoaulic (Fig. 32B). 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 rounded. REMARKS. — Cylichna involuta was originally described from the China Seas as a white species, posteriorly truncate, with a single fold on the columella (A. Adams in Sowerby 1848-50). Hori (2000b) illustrated specimens from Japan that are very similar to the original description of this species. The above description refines the diagnosis of the species by adding the presence of a deep apical perforation and a narrow umbilicus. The material here examined resembles the original description and the redescription by Hori (2000b) and it is therefore assigned to C. involuta . This species is maintained in the genus Cylichna because of the presence of a radula with a denticulate rachidian tooth and several hook-shaped and denticulate lateral teeth, as well as 3 smooth and oval gizzard plates.