Otitoma tropispira, Morassi & Nappo & Bonfitto, 2017

Morassi, Mauro, Nappo, Andrea & Bonfitto, Antonio, 2017, New species of the genus Otitoma Jousseaume, 1898 (Pseudomelatomidae, Conoidea) from the Western Pacific Ocean, European Journal of Taxonomy 304, pp. 1-30 : 12-13

Otitoma tropispira sp. nov.

urn:lsid:zoobank.org:act:85D8CD51-3521-4BEB-B393-80F55132AAF6

Fig. 3 M–R

Etymology

The specific epithet comes from a combination of the Greek ‘ tropis ’ (a keel) and the Latin ‘ spira ’ (spire), alluding to the strong spiral sculpture of the keel-like cords.

Type material

Holotype

NEW CALEDONIA: BATHUS 2, Stn DW 747, S of New Caledonia , 22°30 ′ S, 166°260 ′ E, 574 m ( MNHN IM-2000-32591 ).

Paratypes

NEW CALEDONIA: paratype 1, same data as holotype ( MNHN IM- 2000-32592); paratypes 2 ( MZB 60212) and 3 ( MNHN IM- 2000-32593), SW of New Caledonia, Boulari Passage, 400 m; paratype 4, BATHUS 4, Stn CP946, N of New Caledonia, 20°34 ′ S, 164°58 ′ E, 386–430 m ( MNHN IM- 2000- 32594); paratype 5, BATHUS 1, Stn DW683, off E coast, 20°35 ′ S, 165°07 ′ E, 380–400 m ( MNHN IM- 2000-32595); paratype 6, BATHUS 2, Stn DW758, S of New Caledonia, 22°18 ′ S, 166°11 ′ E, 377– 386 m ( MNHN IM- 2000-32596).

Description

Shell fusiform (b/l 0.34–0.36; a/l 0.42–0.50). Teleoconch of 6–7 convex whorls with periphery at middle on earlier whorls, posterior to mid-whorl on later ones. Suture moderately deep, bordered by a prominent sub-sutural fold bearing a spiral cord, demarcated by a distinctly concave sutural ramp. Sculpture consisting of widely-spaced, narrow, keel-like spiral cords. Four earliest teleoconch whorls with a sub-sutural cord and two cords on abapical half of whorl, increasing to 3 on fifth and 4 on later two whorls. Last whorl with 11–15 spiral cords on base and rostrum. Sutural ramp with a narrow weak cord on its abapical part, becoming stronger on later two whorls (in paratype 5 (MNHN IM-2000-32595) comparable in strength to main spiral cords). Interspaces between spiral cords sculptured by numerous, very fine and faint spiral threads varying in number (up to about 13) ( Fig. 3P ). Axial sculpture represented only by incremental lines, more evident on sutural ramp, where they are arcuate in conformity with curvature of anal sinus. Aperture rather narrow, lanceolate, strongly constricted at entrance to siphonal canal. Siphonal canal long for genus, not notched terminally. Inner lip with moderately thin callus, parietal region with a pad formed at intersection with outer lip. Outer lip edge sharp, preceded by a wide, strong, rounded varix. Stromboid notch distinct, deep. Anal sinus deep, U-shaped, with strongly constricted opening. Protoconch conical, of 2½–2¾ smooth whorls. Protoconch diameter 0.81–0.92 mm ( Fig. 3 Q–R). Color white or cream, with yellowish-orange spiral cords.

Dimensions

Holotype: 16.3 × 5.7 mm, aperture height 8.1 mm. Paratype 2 (largest specimen): 18.8 × 6.4 mm, aperture height 8.5 mm; paratype 6 (smallest specimen): 14.3 × 5.0 mm, aperture height 6.8 mm.

Remarks

Otitoma tropispira sp. nov. is distinguished from its described congeners by its rather large size (attains about 19 mm in maximum length) and the sculpture of its keel-like spiral cords, somewhat reminiscent of members of the pseudomelatomid genus Turridrupa Hedley, 1922 . However, members of that genus have a weak to absent parietal pad, which does not constrict entrance to the anal sinus, and the interior part of the aperture is sculptured by spiral plicae. Furthermore, the protoconch of O. tropispira sp. nov. is smooth, while that of Turridrupa bears axial riblets on the last 1½–2 whorls ( Kilburn 1988; Powell 1966).

Figures

Fig. 3. [next page] A–G. Otitoma xantholineata sp. nov. A–B. Holotype (MNHN IM-2000-32587), Fiji, S of Viti Levu, 18°12.4′ S, 178°33.0′ E, 144-150 m, 7.25 × 3.0 mm. C–G. Paratype 5 (MZB 60211), MUSORSTOM 10, Stn CP1366, Fiji, S of Viti Levu, 18°12.4′ S, 178°33.1′ E, 149–168 m. D. Teleoconch. E. Secondary sculpture of the teleoconch. F–G. Protoconch. — H–I. Drillia batjensis Schepman, 1913, syntype, Batjan, 0°11′ S, 127°25′ E, Indonesia, 397 m, 7.39 × 3.75 mm, (ZMA.MOLL.136858_1). — J–L. Austropusilla (Metaclathurella) crokerensis Shuto, 1983, holotype, Australia, Northern Territory, Arafura Sea, 10°17′00″ S, 132°38′00″ E, ca 45 m (C.134692). — M–R. Otitoma tropispira sp. nov. M–N. Holotype (MNHN IM-2000-32591), BATHUS 2, Stn DW747, S of New Caledonia, 22°30′ S, 166°260′ E, 574 m, 16.3 × 5.7 mm. O–R. Paratype 2 (not coated) (MZB 60212), SW New Caledonia, Boulari Passage, 400m.O. Teleoconch.P. Secondary spiral sculptureof the teleoconch.Q–R. Protoconch. Scale bars: C = 2 mm; D, O = 500 µm; E–G = 200 µm; P–R = 100 μm.