Clavus delphineae, Kilburn, Richard N., Fedosov, Alexander & Kantor, Yuri, 2014

Kilburn, Richard N., Fedosov, Alexander & Kantor, Yuri, 2014, The shallow-water New Caledonia Drilliidae of genus Clavus Montfort, 1810 (Mollusca: Gastropoda: Conoidea), Zootaxa 3818 (1), pp. 1-69 : 23-25

Clavus delphineae new species

( Figs. 7 G, H, 10 A–E)

Drillia (Clavus) mediocris (non Deshayes, 1863); Bouge & Dautzenberg 1914: 140.

Type material. Holotype: Loyalty Islands, Lifou, LIFOU 2000, Baie du Santal, small cove west of the Pointe d'Easo, Stn. 1422, 20°47.1’S, 167°07.4’E, 4 m, MNHN IM–2000–26919; Paratypes: Loyalty Islands, Lifou, LIFOU 2000, Stn. 1422 (5— MNHN IM–2000–26920); Stn. 1419, 20°55.6’S, 167°04.5’E, 5 m (6— MNHN IM–2000–26921); Stn. 1426, 20°45.9’S, 167°06.2’E, 4–7 m (6— MNHN IM–2000–26922); New Caledonia, Koumac, EXPÉDITION MONTROUZIER, Stn. 1319, 20°44.7’S, 164°15.5’E, 15–20 m (12— MNHN IM–2000–26923).

Other new caledonian material examined (total 24 lots, 128 spms, including type material):

New Caledonia, LAGON, Stns. 1145 (1 spm), 1365 (3 spms), 1485 (1 spm);

EXPÉDITION MONTROUZIER, Touho Stn. 1272 (1 spm);

PALEO –SURPRISE, Stn. DW1394 (1 spm).

Loyalty Islands, Lifou: LIFOU 2000, Stns. 1411 (1 spm), 1413 (1 spm), 1419 (6 spms), 1420 (5 spms), 1421 (7 spms), 1422 (30 spms), 1423 (3 spms), 1424 (2 spms), 1425 (13 spms), 1427 (2 spms), 1429 (2 spms), 1438 (2 spms), 1440 (1 spm), 1444 (15 spms), 1448 (4 spms), 1453 (2 spms);

Coral Sea, Chesterfield Plateau, CORAIL 2, Stn. DW117 (1 spm).

Etymology. This attractive little species is named in honour of Delphine Brabant of MNHN, who skilfully sorted the New Caledonian turrid material into morphospecies.

Distribution. New Caledonia, Loyalty Islands and Coral Sea, 3 to 30 m, live specimens to ca 20 m.

Diagnosis. Small (adult length 8.8 to 12.5 mm), breadth/length 0.37–0.43, aperture/total length 0.37–0.42, fasciole weak or absent. Suture shallow, subsutural region concave, adpressed to previous whorl; periphery with angular, node-like axial ribs, in t/s sharp, feeble where they cross subsutural concavity, evanescing at about level of parietal nodule; 8–10 per whorl; rostrum with 5–6 declivous spiral ridges. Surface highly glossy, superficially without microsculpture, but with extremely fine axial striae and even finer spiral striae. Terminal varix rounded, close to lip. White with a broad dark reddish-brown band around middle of last whorl, which often has a row of small whitish spots or dots towards base, subsuturally tinged with grey, lower edge of subsutural concavity with a distinct spiral brown line; concavity immediately behind anal sinus with a dark brown blotch, columella white.

Description. Small (adult length 8.8 to 12.5 mm); claviform, breadth/length 0.37–0.43, aperture/total length 0.37–0.42, whorls strongly concave posteriorly, with somewhat cylindrical last whorl and broadly tapering base, fasciole weakly convex or absent; siphonal canal squarely truncate, very shallowly indented. Outer lip in side view convex, with anal sinus asymmetrically U-shaped, directed adapically, parietal nodule large, stromboid notch moderately deep.

Suture shallow, subsutural region concave, rising high up base of previous whorl, adpressed. Periphery with angular, node-like axial ribs, opisthocline, in t/s sharp, subequal to intervals, feeble where cross subsutural concavity, evanescing at about level of parietal nodule; 8–10 per whorl. Rostrum with 5–6 declivous spiral ridges. Surface very glossy, superficially without microsculpture, but with extremely fine axial striae and even finer spiral striae. Terminal varix rounded, close to lip.

White with a broad deep reddish-brown band around middle of last whorl (showing weakly above suture on spire whorls), this band often bearing a row of small whitish spots or dots at its anterior third, sometimes merging into a spiral band immediately behind lip; subsutural concavity with a grey tinge and its lower margin has a distinct spiral brown line; base white. Protoconch and columella white, parietal nodule brownish-white; subsutural concavity immediately behind anal sinus with a dark brown blotch.

Protoconch ( Fig. 10 D) cylindric-domed, of two nearly smooth whorls, except narrow zone of micropustules along abapical suture. Posteriormost 1/4 of whorl with very fine incremental slightly arcuate lines, and 1/8 of whorl completely covered by micropustules and with very thin spiral line along abapical suture. Diameter about 700 Μm, height about 670 Μm. Protoconch-teleoconch transition indistinct, marked by disappearance of micropustules and spiral line and appearance of strong axial rib.

Measurements. Holotype: 12.1 x 4.7 mm. Largest and smallest adult paratypes: 12.5 x 4.5 mm and 9.3 x 3.8 mm, respectively.

Radula ( Fig. 7 G, H): Rachidian narrow, with straight or even rounded slightly convex anterior edge, with strong median cusp and fine side denticles. Lateral teeth broad, arcuate, with 14 cusps, 3rd–5th from inner side being the longest and gradually diminishing in length towards outer side, where they evanesce. Marginal teeth long, with broader blade about 1/3 of teeth length. Blade edges weakly thickened. Accessory limb narrow, weak but distinct.

Remarks. Clavus delphineae resembles the vidua morph of C. unizonalis in miniature (maximum length ca 12 mm, against ca 22 mm), or (more closely) the similarly small C. protentus Hervier, 1896 , but is distinguishable at a glance by its very high gloss. It further differs in its extremely minute growth lines and spiral striae, and in whorls that are adpressed at the suture, not separated by a narrowly notched suture that undercuts the succeeding whorl; the entire base of the last whorl is pure white (brown to off-white in those two species). It shares the brown spiral line and pale parietal pad of C. protentus , but lacks its subsutural brown blotches.

According to material in the Dautzenberg collection (IRSNB), C. delphineae was the species recorded from New Caledonia as Drillia mediocris (Deshayes, 1863) by Bouge & Dautzenberg (1914). Deshayes’ poor figure shows suture-to-suture axial ribs, without a tubercular periphery or a sunken subsutural area, quite unlike the present species. The unique type of Pleurotoma mediocris , originally in the Maillard collection, cannot now be located; nothing agreeing with it appears to have been collected at the type locality ( Reunion Island) by recent collectors (J. Drivas, M. Jay), and the name should be treated as a nomen dubium.

Figures

FIGURE 7. Radulae of Clavus unizonalis, C. albotuberculatus, C. protentus and C. delphineae. A, B. Clavus unizonalis, Loyalty Islands, Lifou, LIFOU 2000, Stn. 1424, SL 20.1 (shell—Fig. 6 D); C, D. Clavus albotuberculatus, LAGON, Stn. 445, SL 56.8 mm (shell—Fig. 8 C, D); E, F. Clavus protentus, Loyalty Islands, Lifou, LIFOU 2000, Stn. 1433, SL 13.5 mm (shell—Fig. 9 G); G, H. Clavus delphineae, Loyalty Islands, Lifou, LIFOU 2000, Stn. 1422, SL 10.1 mm (shell—Fig. 10 E).

FIGURE 10. Clavus delphineae n. sp. A, B. Holotype; C. Paratype, MNHN IM – 2000 – 26921, 12.3 x 5.2 mm; D. Protoconch, Loyalty Islands, Lifou, LIFOU 2000, Stn. 1422, 3.3 mm; E. Radula voucher, Loyalty Islands, Lifou, LIFOU 2000, Stn. 1422, SL 10.1 mm (radula—Fig. 7 G, H).