Triforis (Mastonia) leucomys Hervier 1898

Triforis (Mastonia) leucomys Hervier, 1898

(Fig. 20)

Triforis (Mastonia) leucomys Hervier, 1898: 261, illustrated by Hervier (1899: pl. 17, fig. 5).

TYPE LOCALITY. — Lifou, New Caledonia.

TYPE MATERIAL. — Syntype. New Caledonia • MNHN-IM-2000-1484; 1 specimen; from type locality.

ORIGINAL DESCRIPTION. — T. sinistrorsa, ovata, ventricosa, apice acuminatim attenuata, solidula, nitida, alba, prope apicem brunneo bilirata, ad basin circa canalem et labrum ustulato-rufo tincta. Anfractus 12-15; embryonales 3 bicarinati, striati, pallidè cornei, intermedii sutura indistincta, lineari discreti, costulis et liris ornati. Costulae rotundae, laeves, biseriatim tuberculiferae, tuberculis subrotundis, aequalibus. Lirae elevatae 2, costulis minores, gemmas religando superantes; aliquando, praesertim in inferioribus anfr., intermediae 2 lirulae, multò graciliores, in sulcis inter gemmarum series decurrentes. Ultimus anfractus subconvexus, liris 5 graniferis (prima majore, caeteris decrescentibus) cingulatus, ad ortum canalis vix compressus. Canalis basalis brevis, unicarinatus, obliquus, valdè recurvus, tubulatus, semiclausus, brunneo tinctus. Apertura subtubulata, prominens, superné obliquè arcuata et lateraliter ad suturam fissa, post fissuram rotundè sinuata. Columella arcuata, interna. Labrum tubiforme, propè aperturam brunneo tinctum, canali basali et lateri columellari cohaerens, infrà rotundum, lateraliter planatum, supernè anfr. penultimum transiens, non adhaerendo, et in latere sinum subrotundum efformans. — Long. 6 mill.; diam. max. 2.25 mill.

Hab. Insula Lifou. Vidi 5 specimina, à R. P. Goubin, S. M., collecta.

TRANSLATION OF THE LATIN TEXT. — Sinistral shell, ovate, broad, acute and slender apex, rather solid, bright, white, with two brown spiral cords near the apex, at the base near the siphon and the lip it is coloured in brownish-red. Whorls are between 12 and 15; three embryonic whorls with two keels, striated, light brownish, intermediate whorls are separated by a linear and indistinct suture and are adorned by ribs and spiral cords. Ribs are rounded, smooth, with two series of tubercles, which are slightly rounded, equal. There are two elevated spiral cords, smaller than the ribs, with tubercles at the crossings. In some cases, especially in the inferior whorls, interspaces between gemmule series are characterised by two very thin intermediate spiral cords. Last whorl slightly convex, adorned by five granulated spiral cords (first cord is bigger, the others smaller), near the siphon is barely shrunk. Siphon is short, unicarinated, oblique, strongly curved, tubular, partly closed, coloured in brown. Slightly tubular aperture, protruding, above obliquely arched and laterally fissured towards the suture, after the fissure it is roundly curved. Arched and internal columella. Tubular lip, coloured in brown near the aperture, adjacent to the siphon and to the columellar side, rounded below, flattened laterally, surpassing the second last whorl, unattached, and laterally forming a slightly rounded sinus. — Length 6 mm; maximum diameter 2.25 mm.

Locality: Lifou Island. I saw 5 specimens collected by R. P. Goubin.

DIAGNOSIS. — Shell cyrtoconoid with flat sides. Syntype 5.4 mm high. Teleoconch of c. 10 whorls. Three spiral cords present, the second appearing on the last whorl. First and third cords with tubercles at the intersection with rather prosocline axial ribs. Second cord with tubercles. A smooth thread present suprasuturally. Peristome with additional cords below the second and third cord. Posterior sinus shallow. Base with three additional cords, the first with tubercles, the other two smooth. First 2.5 teleoconch whorls white, the following yellowish. Third and fourth teleoconch whorls with part of the first and third cord brown creating a strong line between the white whorls above and the yellow whorls bellow. The peristome margin and the tip of the siphonal canal brown.