Gadilina lauensis, Scarabino & Scarabino, 2010

Scarabino, Victor & Scarabino, Fabrizio, 2010, A new genus and thirteen new species of Scaphopoda (Mollusca) from the tropical Pacific Ocean, Zoosystema 32 (3), pp. 409-423 : 414

Gadilina lauensis n. sp.

( Fig. 1G, P-T)

TYPE MATERIAL. — Fiji. Lau Ridge , BORDAU 1 , stn CP 1400, 16°28’S, 179°50’W, 1004-1012 m, 1 lv holotype ( MNHN 22780 ) ; 3 dd paratypes ( MNHN 22781 ) .

TYPE LOCALITY. — Fiji, Lau Ridge, 16°28’S, 179°50’W, 1004-1012 m ( BORDAU 1, stn CP 1400).

ETYMOLOGY. — From Lau Ridge, the type locality.

OTHER MATERIAL EXAMINED. — Fiji. Lau Ridge, BOR DAU 1, stn CP 1400, 16°28’S, 179°50’W, 1004-1012 m, 3 dd.

DISTRIBUTION. — Fiji. Live at 1004-1012 m.

DESCRIPTION

Shell 58.8 mm long, slender, smooth, polished, translucent, rather strongly curved and thin-walled. Transverse section suboval throughout, slightly flattened on dorsal side and rounded ventrally. Anterior aperture straight, apex with a thick callus and lumen slightly oval.

Radula: rachidian tooth slightly curved in section, anterior margin irregular, internal face irregularly rough with a medial knob; lateral teeth wide, head roughly granulose, with three major primary cusps, the central quite pointed, and five small denticles on the internal face; marginal teeth sinusoidal, with a small cusp in the anterior angle connecting with laterals.

Measurements of holotype: L 58.8, W 3.42-3.2, w 0.65, arc 5 at 26 from apex.

REMARKS

The most similar species to G. lauensis n. sp. is Gadilina pachypleura ( Boissevain, 1906) (syntypes ZMA 3.06.063, ZMA 3.06.064, examined) from Indonesia at 1788-1886 m depth ( Boissevain 1906). The new species is more curved and tapering, and has a larger and straighter anterior aperture. Gadilina insolita ( Smith, 1894) , widely distributed in the Indo-Pacific region, has a highly variable shell outline, especially in the morphology of the apical region, from a wide apex and a very thick apical callus with a small lumen to a long tapering apical area without a clear callus ( Smith 1894; Scarabino 1995: fig. 95a, b). In young specimens, the vestiges of longitudinal threads are clearly visible in the apical area. Also, the transverse section of the shell varies from roughly oval to triangular with the dorsal side straight in the apical area in extreme forms (V. Scarabino pers. obs.). Gadilina lauensis n. sp. is the third living species known in the genus. The radula of G. insolita (illustrated by Scarabino 1995: fig. 90) is quite similar and confirms that this character is appropriate for identification of the genus.

Subfamily EPISIPHONINAE Chistikov, 1975