Clavus bilineatus (Reeve, 1845)

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 : 25-28

Clavus bilineatus (Reeve, 1845)

( Figs. 11 A–I, 12 A, B)

Pleurotoma bilineata Reeve 1845 : pl. 25, sp. 225.

Other references.

Pleurotoma (Clavus) bilineatus ; Melvill & Standen 1895: 137; Bouge & Dautzenberg 1914: 137. Clavus bilineatus ; Powell 1966: 71; Wells 1991: 6, pl. 2, figs. 3–4 (syntype); Wilson 1994: 184, pl. 40, fig. 6; Sysoev in Poppe 2008: pl. 675, figs. 10–11 only.

Type data. Three syntypes NHMUK 1963475, of which the two larger have a damaged lip (largest type 17.3 x 6.3 mm); the smallest (13.3 x 5.2 mm) and most complete syntype is here illustrated. Type locality: Capul and Mindoro Islands, Philippines, 15 fath. [27 m].

New caledonian material examined (total 49 lots, 109 spms):

New Caledonia, LAGON Stns. 68 (1 spm), 131 (1 spm), 336 (1 spm), 661 (1 spm), 712 (1 spm), 713 (1 spm), 731 (1 spm), 852 (1 spm), 855 (2 spms), 880 (1 spm), 901 (1 spm), 940 (1 spm), 1159 (1 spm), 1235 (1 spm), 1334 (9 spms), 1336 (5 spms), 1345 (1 spm), 1346 (1 spm), 1352 (1 spm); 1356 (1 spm); 1357 (1 spm), 1370 (3 spms);

EXPÉDITION MONTROUZIER, Koumac Stns. 1310 (3 spms), 1312 (2 spms), 1319 (2 spms); Touho Stns. 1245 (2 spms), 1254 (2 spms), 1260 (2 spms), 1270 (1 spm), 1271 (5 spms), 1272 (5 spms), 1273 (9 spm).

Loyalty Islands, Nouméa: Campagne d'essais 1987 Stns. DE 07 (1 spm), DE 08 (1 spm), DE 70 (1 spm);

Lifou: LIFOU 2000, Stns. 1421 (1 spm), 1422 (1 spm), 1424 (2 spms), 1439 (1 spm), 1443 (1 spm), 1444 (1 spm), 1451 (1 spm).

Coral Sea, Chesterfield Plateau: CORAIL 2, Stns. DW77 (1 spm); DW103 (2 spms), DW108 (1 spm); DW160 (1 spm). CHALCAL Stn. D17 (2 spms)

Distribution. Mauritius to Philippines, Marshall Islands, New Caledonia, Loyalty Islands and Tahiti, living from intertidal to 70 m, in our material confirmed live to ca 35 m.

Description. Shell thick, claviform, with orthoconoid spire, adult length to 17.5 mm, breadth/length 0.40–0.43, aperture/total length 0.41–0.42 in New Caledonian specimens. Teleoconch of about seven whorls in adult specimens. Periphery of spire whorls strongly shifted abapically. Suture distinct, adpressed to previous whorl; base broad, fasciole distinct in adult shells. Outer lip with widely open U-shaped anal sinus, slightly constricted by a large parietal pad, and distinct stromboid notch. No subsutural cord or sulcus. Terminal varix situated slightly behind lip. Axial ribs almost orthocline on early 1–2 whorls and distinctly opisthocline on later whorls, 9–11 on last adult whorl. Ribs less pronounced on subsutural slope and very feeble at parietal level, though well developed at periphery, notably projecting and somewhat squamiform in some specimens. Spiral sculpture of 8–10 coarse, declivous ridges on fasciole; lower part of last whorl at parietal level with a row on nodules on secondary radial riblets; surface covered with dense, rather rugose, microscopic spiral threads, and coarser collabral ones.

Subsutural region and shell base light-brown or pale, whorl peripheries marked with light spiral band, fringed with dark-brown line interrupted at axial ribs from below and a finer one from above. Basal nodules (when present) white.

Protoconch ( Fig. 11 I) domed, of two nearly smooth whorls, posteriormost 1/4 of whorl with very fine incremental slightly arcuate lines. Diameter about 650 Μm, height about 550 Μm. Protoconch-teleoconch transition indistinct, marked by change in suture morphology and appearance of strong axial rib.

Radula ( Fig. 12 A, B): Rachidian narrow, with rounded slightly convex anterior edge, with medium-sized median cusp and fine side denticles. Lateral teeth broad, arcuate, with 14 cusps, 2nd–4th from inner side being the longest and gradually diminishing in length towards outer side, where they evanesce. Marginal teeth long, narrow, with slightly broader blade about 1/4 of teeth length. Blade edges very weakly thickened. Accessory limb narrow, weak. About 40 rows of teeth.

Remarks. Clavus bilineatus was well described by Wells (1991), who illustrated syntypes. The largest and smallest adults from New Caledonia in MNHN measure 17.0 x 6.9 mm and 12.8 x 5.4 mm, respectively.

Although Clavus bilineatus was confused by some early authors with Pleurotoma pulchella Reeve, 1845 , Wells demonstrated their distinctness. Moreover, we have seen nothing from the Indo-West Pacific that resembles the types of P. pulchella , and suspect that direct comparison may prove it to be an earlier name for the tropical West Atlantic Fenimorea halidorema Schwengel, 1940 .

Figures

FIGURE 11. Clavus bilineatus (Reeve, 1845). A, B. Syntype of Pleurotoma bilineatus, NHMUK 1963473, Philippines, “ Capul and Mindoro Islands ”, 15 fath. [27 m], 13.3 x 5.2 mm; C, D. Loyalty Islands, Lifou, LIFOU 2000, Stn. 1422, 16.9 x 7.0 mm; E. Loyalty Islands, Lifou, LIFOU 2000, Stn. 1439, 17.0 x 6.8 mm; F. New Caledonia, LAGON Stn. 713, Canala Sector, SL 15.1 mm; G. Philippines, Balicasag Is, lumun-lumun net, 60 – 80 m, SL 14.2 mm; H. Radula voucher, LAGON, Stn. 68, Ile Ouen-Baie du Prony, SL 13.8 mm (radula—Fig. 12 A, B); I. Protoconch, New Caledonia, EXPÉDITION MONTROUZIER Touho, Stn. 1242, SL 3.3 mm.

FIGURE 12. Radulae of Clavus bilineatus, C. lamberti; C. obliquicostatus and C. formosus. A, B. Clavus bilineatus, LAGON, Stn. 68, SL 13.8 mm (shell—Fig. 11 H); C, D. Clavus lamberti, New Caledonia, EXPÉDITION MONTROUZIER, Touho Stn. 1273, SL 10.4 mm (shell—Fig. 13 E); E, F. Clavus obliquicostatus, New Caledonia, EXPÉDITION MONTROUZIER, Koumac Stn. 1283, SL 12.6 mm (shell—Fig. 14 I); G, H. Clavus formosus (shell—Fig. 16 F).