Belomitra admete, Kantor & Puillandre & Rivasseau & Bouchet, 2012

Kantor, Yuri I., Puillandre, Nicolas, Rivasseau, Audrey & Bouchet, Philippe, 2012, 3496, Zootaxa 3496, pp. 1-64 : 26

Belomitra admete new species

Figures 11, 13A–C, 14

Type material: Holotype MNHN 24485 (measurements: SL 16.4 mm, BWL 11.2, AL 8.6, SW 6.8 mm), 3 paratypes MNHN 24486 .

Type locality: West of Sri Lanka, 06º59’N, 78º50’E, 2540 m, 1 Aug. 1981 [SAFARI 2 sta. CP05] .

Material examined: INDIAN OCEAN. SAFARI 2, sta. CP05, 06º59’N, 78º50’E, 2540 m, 3 lv, 1 dd (holotype and three paratypes).

Description (holotype, Fig. 14A–D): Shell thin but solid, turriform, with high elevated spire, consisting of 4+ moderately convex whorls. Apical whorls decollated. Suture deeply impressed. Subsutural ramp well pronounced, narrow, very slightly concave, delimitated by row of smaller beads on subsutural cord and stronger row of rounded beads on shoulder. Beside inconspicuous growth lines, axial sculpture consisting of sharp, narrow, broadly spaced, prosocline ribs, 13 on penultimate and 15 on last whorl, extending over whole whorl height on spire whorls, less pronounced on last whorl and becoming obsolete on shell base. Spiral sculpture of indistinct, low, narrow cords, except on subsutural ramp, better pronounced on spire whorls where flat interspaces are about equal to cords width, unevenly strong but overall weaker, and irregularly spaced on last whorl, distinct, raised and widely spaced on canal. Aperture medium high, elongate oval. Outer lip chipped, thin, concave adapically, convex and evenly rounded abapically. Columella nearly straight, smooth, without plaits, with strong siphonal fold. Callus narrow, of thin transparent glaze overlying parietal region. Siphonal notch absent. Canal short, slightly curved to left. Shell colour off-white. Periostracum thin, very light olive, smooth, tightly adherent. Operculum leaf-shaped, with eroded terminal nucleus.

Radula of holotype ( Fig. 13A–C) examined from dehydrated body. Holotype is mature or semi-mature male, with simple medium-long penis gradually narrowing towards tip without distinct seminal papilla. Head very short, with rather long head tentacles, eyes absent. Radula of approximately 70 rows of teeth, 1.65 mm long (0.19 AL), narrow, about 65 µm in width (0.76% of AL). Lateral teeth about 65 µm in maximum length (0.76% of AL), with narrow base, attached to membrane at 8–12º to longitudinal axis. Lateral teeth bicuspid, inner cusp longer than outer one. Rachidian teeth closely spaced and significantly overlapping each other. Tooth base with strongly notched anterior edge, which is better seen when tooth is not overlapped by adjoining row ( Fig. 13A). Three closely spaced robust cusps, central longest, emanate from the anterior edge of tooth base and are recurved in side view ( Fig. 13C).

Distribution: Known only from type locality ( Fig. 11).

Etymology: The shell outline superficially recalls Admete, a genus of Cancellariidae , and the name is used as a noun in apposition.

Remarks: Two adult paratypes with shell length 15.3 (dead collected) and 13.9 mm (live collected) are very similar to the holotype. A juvenile with SL 3.8 mm already has a dissolved spire tip.

Belomitra admete is somewhat similar to B. decapitata , also occurring at abyssal depths in the Indian Ocean. It differs from it in having a smaller shell, less numerous and more poorly developed axial ribs, and less pronounced spiral cords. It also differs in the radula, particularly in the shape of the rachidian, which has much more robust and elevated cusps in B. admete .