Otitoma xantholineata, 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 : 9-10

Otitoma xantholineata sp. nov.

urn:lsid:zoobank.org:act:118559C3-5952-4DD8-84A3-5F1F64FD0F42

Fig. 3 A–G

Etymology

The specific epithet comes from the Greek ‘ xanthos ’ and Latin ‘ lineata ’, alluding to the brownish orange spiral cords.

Type material

Holotype

FIJI ISLANDS: MUSORSTOM 10, Stn CP 1363, S of Viti Levu , 18°12.4 ′ S, 178°33.0 ′ E, 144–150 m ( MNHN IM-2000-32587 ).

Paratypes

FIJI ISLANDS: paratypes 1–2, MUSORSTOM 10, Stn DW1365, S of Viti Levu, 18°12.7 ′ S, 178°32.4 ′ E, 295–302 m ( MNHN IM- 2000-32588); paratype 3, MUSORSTOM 10, Stn CP1366, S of Viti Levu,

18°12.4 ′ S, 178°33.1 ′ E, 149–168 m ( MNHN IM- 2000-32589); paratype 5, MUSORSTOM 10, Stn CP1366, same locality as preceding ( MZB 60211).

SOLOMON ISLANDS: paratype 4, SALOMON 1, Stn DW1850, 10°28.1 ′ S, 161°59.0 ′ E, 139–261 m ( MNHN IM- 2000-32590).

Description

Shell cylindric-fusiform (b/l 0.37–0.41; a/l 0.48–0.54). Teleoconch of 4–5 weakly and evenly convex whorls with periphery at mid-whorl height. Suture shallow and bordered by a sub-sutural fold with a prominent spiral cord. Sutural ramp concave on earlier whorls, more shallowly concave on later ones. Axial sculpture absent (holotype) or consisting of ribs restricted to earlier two teleoconch whorls. Spiral sculpture consisting of prominent, angular and well-spaced cords. First two teleoconch whorls with a sub-sutural cord and two cords between sutural ramp and whorl base, increasing to 3 on antepenultimate whorl, 3–4 and 4–5 on penultimate and last whorl, respectively. Sutural ramp sculptured with none (usually first whorl) to 1 weak cord on earlier whorls; later two whorls with two spiral cords, abapical one strongest. Last whorl with 12–14 spiral cords on base and rostrum. Interspaces between spiral cords lacking secondary sculpture ( Fig. 3E ). Surface covered only by relatively coarse axial incremental lines. Aperture pyriform, constricted at entrance to siphonal canal. Siphonal canal relatively wide, expanding slightly distally, oblique, not notched. Inner lip covered with thin callus, most of its parietal region occupied by a thin pad. Outer lip edge sharp, preceded by a wide, low and rounded varix. Stromboid notch distinct. Anal sinus U-shaped, its entrance only slightly constricted by parietal pad. Protoconch domed, of 1½–1¾ smooth whorls with distinct protoconch/teleoconch transition, white, diameter 0.77– 0.90 mm ( Fig. 3 F–G). Teleoconch yellowish-white to pale orange-yellow, with light brownish orange spiral cords and aperture edged with brownish orange.

Dimensions

Holotype: 7.25 × 3.0 mm, aperture height 3.8 mm. Paratype 3: 8.8 × 3.35 mm, aperture height 4.6 mm; paratype 4: 8.5 × 3.2 mm, aperture height 4.6 mm.

Remarks

Otitoma xantholineata sp. nov. is similar in shape and number of spiral cords to O. kagoshimaensis from the Upper Pleistocene of Moeshima Island, Japan (3 on first teleoconch whorl increasing to 4–5 on later whorls), based on a single specimen of the latter, which is lacking the spire apex. However, O. kagoshimaensis is sculptured by axial ribs on all teleconconch whorls ( Shuto 1965: 156), while in O. xantholineata sp. nov. axial sculpture is absent or restricted to earlier teleoconch whorls. In O. kagoshimaensis the interspaces between spiral cords are “covered by numerous minute spiral lines”, while O. xantholineata sp. nov. has no interstitial sculpture. Furthermore, O. xantholineata sp. nov. has a more shallowly concave sutural ramp compared to O. kagoshimaensis . Otitoma xantholineata sp. nov. is superficially similar to two Recent species: Drillia batjanensis Schepman, 1913 from Indonesia ( Fig. 3 H–I) and O. crokerensis ( Shuto, 1983) from the Arafura Sea ( Fig. 3 J–L). Otitoma xantholineata sp. nov. is readily distinguished from D. batjanensis in protoconch structure (domed, of 1½–1 ¾ whorls rather than bluntly conical, of 3 whorls), and by spiral sculpture features. The two species have a comparable number of spiral cords on spire whorls, but these are of nearly uniform strength in Otitoma xantholineata sp. nov., while in D. batjensis they are more “keel-like”, with those on abapical side of the whorl more prominent than the others. Furthermore, O. xantholineata sp. nov. has vestigial axial sculpture on earlier whorls and distinct axial incremental lines on the entire surface, while there is no indication of axial sculpture in D. batjensis . Otitoma xantholineata sp. nov. may superficially resemble O. crokerensis ( Shuto, 1983) , from which it is distinctly different in protoconch features ( O. crokerensis has the same protoconch structure as D. batjensis ), in having fewer and narrower spiral cords, in the profile of spiral whorl(evenly convex instead of slightly shouldered) and in the more defined siphonal canal.

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.