Cylichna, Loven, 1846

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 651-652

Genus CYLICHNA Lovén, 1846

Cylichna Lovén, 1846: 10 . Type species: Bulla cylindracea Pennant, 1777 [Recent, British Isles], by subsequent designation of Herrmannsen (1852 [in 1846-52]).

Synonyms:

Bullina Risso, 1826: 51 [non Bullina Férussac, 1822 – Family Bullinidae ]. Type species: Bulla cylindrica Bruguière, 1792 [= Cylichna cylindracea (Pennant, 1777) ; Recent, Mediterranean and eastern Atlantic], by subsequent designation of Gray (1847).

Cylindrella Swainson, 1840: 326 [non Cylindrella Swainson, 1840: 311 – Family Conidae , nor Cylindrella Pfeiffer, 1840 – Family Urocoptidae ] (suppressed by ICZN 1974). Type species: Cylindrella alba Swainson, 1840 [= Cylichna cylindracea (Pennant, 1777) ; Recent, Mediterranean and eastern Atlantic], by monotypy.

Bullinella Newton, 1891: 265 [Replacement name for Bullina Risso, 1826 ].

Cryptaxis Jeffreys, 1883: 400 [non Cryptaxis Lowe, 1855 – Family Helicidae ]. Type species: Cylichna parvula Jeffreys, 1883 [Recent, Mediterranean], by original designation.

Clistaxis Cossmann, 1895: 90 [Replacement name for Cryptaxis Jeffreys, 1883 ].

Eocylichna Kuroda & Habe, 1952: 55 [not available]; Kuroda, Habe, & Oyama 1971: 293, 468. Type species: Cylichna braunsi Yokoyama, 1920 [= Cylichna biplicata A. Adams in Sowerby, 1850; Pleistocene, Japan], by original designation.

DIAGNOSIS. — Shell morphology. Shell external, oval to elongate, with a flat, concave or involute spire. Aperture longitudinal, normally as long as the shell, anteriorly rounded. Columella simple. Operculum absent.

Anatomy. Rhinophores absent. Headshield with 2 blunt posterior extensions. Parapodia absent. Digestive system with 3 simple, oval gizzard plates. Radula with a rachidian tooth and several hamate lateral teeth. Reproductive system monaulic. Penis unarmed.

REMARKS. — Risso (1826) introduced the name Bullina for several species of “cephalaspidean” heterobranchs belonging to different groups. One of the species included was Bulla cylindrica Bruguière, 1792 [= Cylichna cylindracea (Pennant, 1777) ], which was subsequently designated as the type species by Gray (1847). Bullina Risso, 1826 is preoccupied by Bullina Férussac, 1822 .

Swainson (1840) introduced the name Cylindrella twice independently in the same work; the first time as a subgenus of Conus Linné, 1758 , and the second time as an opisthobranch genus, with Cylindrella alba Swainson, 1840 as the type species by monotypy. The latter takes precedence according to the Code (ICZN 1999: Article 56.3). However, the name Cylindrella was subsequently suppressed (ICZN 1974).

Cylichna Lovén, 1846 , type species C. cylindracea , is the earliest available name for this genus and Cryptaxis Jeffreys, 1883 is a junior synonym (see Pilsbry 1893). Bullinella Newton, 1891 is a replacement name for Bullina Risso, 1826 , and therefore a junior synonym of Cylichna .

Kuroda & Habe (1952) described the genus Eocylichna for Cylichna braunsi Yokoyama, 1920 . Examination of the anatomy of this species, which is a junior synonym of Cylichna biplicata A. Adams in Sowerby, 1850 (see below), revealed no consistent differences from other species of Cylichna and therefore Eocylichna is here regarded as a junior synonym of Cylichna .

Lemche (1956) studied the anatomy and histology of several species of Cylichna from the north Atlantic and provided comprehensive descriptions. The above diagnosis of the genus is based on this paper and the anatomical descriptions by Thompson (1976) of Cylichna cylindracea .