Clavus obliquicostatus (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 : 30-32

Clavus obliquicostatus (Reeve, 1845)

( Figs. 12 E, F, 14 A–I)

Pleurotoma obliquicostata Reeve 1845 : pl. 20, sp. 168.

Clavus leforestieri Hervier 1896a: 143 ; Hervier 1896b: 59, pl. 1, fig. 6, n. syn. Drillia (Clavus) leforestieri var. albina Bouge & Dautzenberg, 1914: 140 , n. syn. Other references.

Drillia (Drillia) obliquicostata ; Tryon 1884: 204, pl. 12, fig. 12; Schepman 1913: 418. Pleurotoma (Drillia) obliquicostata ; Melvill & Standen 1895: 94. Drillia (Clavus) leforestieri ; Bouge & Dautzenberg 1914: 140.

Type data. Pleurotoma obliquicostata: Three syntypes NHMUK 1991048; type locality unknown. Clavus leforestieri : four possible syntypes (labelled “ Type?” by E. Fischer-Piette in the collection and refered to as “ paratypes ” in Fischer-Piette 1950) in MNHN IM–2000–3067 (freshest illustrated here—fig 14 C, D) 15.7 x 6.4 mm; type locality: New Caledonia and Lifou. Drillia (Clavus) leforestieri var. albina : types not located (originally in Bouge colln); type locality: Île des Pins, New Caledonia.

New caledonian material examined (total 199 lots, 513 spms):

New Caledonia, EXPÉDITION MONTROUZIER, Koumac Stns. 1282 (7 spms), 1283 (15 spms), 1286 (8 spms), 1292 (11 spms), 1297 (4 spms), 1299 (4 spms), 1301 (2 spms), 1302 (6 spms), 1304 (4 spms), 1305 (3 spms), 1306 (7 spms), 1307 (2 spms), 1309 (6 spms), 1323 (1 spm); Touho Stns. 1240 (1 spm), 1242 (35 spms), 1246 (3 spms), 1264 (1 spm); Bourail Stns. 1324 (7 spms), 1326 (1 spm);

Nouméa: Campagne d'essais 1987 Stns. DE 30 (1 spm), DE 36 (1 spm), DE 37 (7 spms), DE 38 (3 spms), DE 39 (2 spms), DE 42 (5 spms), DE 43 (4 spms), DE 46 (3 spms), DE 48 (2 spms), DE 51 (3 spm), DE 52 (2 spms), DE 54 (2 spms), DE 56 (1 spm), DE 58 (2 spms), DE 60 (1 spm);

LAGON Stns. 1 (1 spm),2 (1 spm), 7 (6 spms), 8 (7 spms), 21 (1 spm), 25 (1 spm), 36 (1 spm), 49 (2 spms), 50 (2 spms), 51 (4 spms), 55 (2 spms), 56 (1 spm), 60 (1 spm), 64 (1 spm), 66 (1 spm), 69 (1 spm), 71 (1 spm), 80 (2 spms), 84 (1 spm), 92 (2 spms), 98 (4 spms), 100 (1 spm), 101 (1 spm), 104 (1 spm), 119 (1 spm), 166 (1 spm), 170 (3 spms), 175 (2 spms), 186 (5 spms), 192 (1 spm), 212 (3 spms), 214 (1 spm), 216 (4 spms), 200 (1 spm), 217 (1 spm), 252 (1 spm), 279 (1 spm), 284 (1 spm), 290 (1 spm), 291 (1 spm), 293 (1 spm), 303 (1 spm), 311 (1 spm), 334 (1 spm), 336 (1 spm), 339 (1 spm), 340 (4 spms), 346 (1 spm), 438 (2 spms), 440bis (2 specimens), 455 (1 spm), 468 (2 spms), 481 (1 spm), 542 (1 spm), 545 (2 spms), 546 (1 spm), 547 (2 spms), 555 (1 spm),696 (1 spm), 762 (1 spm), 772 (1 spm), 801 (1 spm), 856 (1 spm), 863 (1 spm), 864 (1 spm), 866 (1 spm), 896 (1 spm), 912 (1 spm), 913 (11 spms), 914 (1 spm), 915 (3 spms), 916 (1 spm), 920 (1 spm), 922 (4 spms), 924 (4 spms), 932 (10 spms), 936 (2 spms), 940 (1 spm), 941 (1 spm), 943 (3 spms), 944 (2 spms), 945 (1 spm), 947 (1 spm), 953 (3 spms), 954 (1 spm), 955 (1 spm), 961 (3 spms), 982 (1 spm), 984 (4 spms), 985 (10 spms), 989 (5 smps), 990 (2 spms), 1004 (1 spm),1007 (1 spm), 1008 (3 spms), 1009 (1 spm), 1011 (11 spms), 1012 (2 spms),1015 (3 spms), 1016 (1 spm), 1018 (1 spm), 1025 (2 spms), 1026 (1 spm),1034 (1 spm), 1037 (1 spm), 1039 (2 spms), 1040 (1 spm), 1041 (3 spms), 1042 (4 spms), 1043 (7 spms), 1044 (2 spms), 1045(10 spms), 1063 (1 spm), 1072 (3 spms), 1168 (3 spms), 1181 (1 spm), 1182 (1 spm), 1198 (1 spm), 1205 (3 spms), 1334 (1 spm),1358 (1 spm), 1367 (8 spms), 1501 (1 spm), 1503 (1 spm);

PALEO –SURPRISE, north New Caledonia, Stns. DW1382 (2 spms), DW1384 (1 spm), 1396 (1 spm).

Loyalty Islands, PLOUVEAL, Stns. 1221 (4 spms), 1222 (1 spm),1223 (1 spm), 1229 (1 spm), 1230 (1 spm);

Lifou: LIFOU 2000, Stns. 1424 (2 spms), 1447 (1 spm), 1463 (1 spm);

Loyalty Ridge, MUSORSTOM 6, Stn. DW430 (1 spm).

Coral Sea, Lansdowne–Fairway, CORAIL 2, Stns. DW01 (1 spm), DW10 (2 spms);

Chesterfield Plateau, CORAIL 2, Stns. DW31 (1 spm), DW32 (3 spms), DW34 (9 spms), DW38 (1 spm), DW40 (3 spms), DW44 (1 spm), DW45 (2 spms), DW70 (1 spm), DW71 (1 spm), DW72 (5 spms), DW77 (1 spm), DW87 (2 spms), DW101 (1 spm), DW103 (1 spm), DW122 (3 spms), DW128 (1 spm), DW138 (1 spm), DW145 (4 spms), DW163 (1 spm); Chesterfield–Bellona Plateau, CHALCAL 1, Stns. DC28 (1 spm), DC45 (2 spm), DC49 (1 spm), DC55 (1 spm), DC61 (1 spm).

Distribution. Eastern Indonesia and Philippines to New Caledonia, 2 to ca 100 m, sand, coral and corall debris, in our material confirmed live to ca 60 m.

Description. Claviform, adult length 9.4–20.4 mm, with orthoconoid spire (breadth/length 0.37–0.43, aperture/total length 0.35–0.46) and broadly tapering, truncate base, end of siphonal canal oblique, shallowly to deeply notched, fasciole evenly convex, occasionally with slight false umbilicus. Anal sinus linguiform, deep, adapically directed, weakly constricted by a parietal pad; outer lip distinctly alate, in side view gently convex, sometimes feebly crenulate, with deep stromboid notch.

Whorls concave subsuturally, tops of ribs sometimes bulging slightly below suture. Axial ribs suture-to-suture on early whorls, developing a shallow concavity at about 0.3 of each whorl below the suture, gradually weakening at suture, obsolete on rostrum or occasionally at level of parietal nodule, eight on first whorl, 10–13 on penultimate whorl, in t/s angularly rounded, wider than their intervals, becoming wavy or bifurcating on base; last whorl with a rounded varix, ca 0.25 back from lip. Base of last whorl with 12–14 weak spiral ridges, becoming even weaker adapically and evanescing towards shoulder, plus 5–7 rather weak, rounded ridges on rostrum; sometimes a few faint spiral striae below suture. Maximum length.

Colour variable: light to dark brown (usually concentrated in a band around middle of last whorl) with paler brown to white ribs, base of last whorl off-white to buff; often whitish overall, tinged between ribs with brown. Aperture brown, margin white.

Protoconch ( Fig. 14 J) distinctly papilliform, with two smooth whorls, first one depressed, surface smooth, but under higher magnification, it is seen that sutural region is slightly pustulose and there are a series of very fine plicules below suture. Diameter ca 690 µm, height 730 µm. Protoconch-teleoconch transition is marked by strongly sinuous axial riblet.

Measurements. Largest and smallest undamaged adults: 17.3 x 6.0 mm and 9.4 x 4.0 mm, respectively.

Radula ( Fig. 12 E, F): Rachidian very narrow, anterior edge indistinct, with strong single cusp, that is shorter than tooth base. Posterior edge of tooth base rounded, fusing into membrane with indistinct border. Lateral teeth medium broad, arcuate, with 11 cusps, 2nd–4th from inner side being the longest and gradually diminishing in length towards outer side, where they evanesce. Marginal teeth medium long, broad, with slightly broader long blade. On anterior edge of the tooth blade constitutes 2/3 of teeth length, on posterior edge slightly more than 1/3 of tooth length. Blade edges very weakly thickened. Accessory limb weak. About 30 rows of teeth.

Remarks. Originally described without locality, Pleurotoma obliquicostata was recorded by Schepman (1913) from Sulu Is. ( Philippines) and Kei Is. ( Indonesia), also as “subfossil specimens” from Celebes [Sulawesi]. In the following year Melvill & Standen (1895) reported P. obliquicostata from Lifou. Although Bouge & Dautzenberg (1914: 140) rejected this record as “certainement erroné”, comparison between syntypes of Pleurotoma obliquicostata and author’s specimens (syntypes?) of Clavus leforestieri , reveals no difference. Judging by the New Caledonian samples examined, Clavus obliquicostatus is the most abundant of the larger drilliids in the area.

Figures

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).

FIGURE 14. Clavus obliquicostatus (Reeve, 1845). A, B. Pleurotoma obliquicostata, syntype NHMUK 1991048; type locality unknown; C, D. Possible syntype of Drillia leforestieri (Hervier, 1896), MNHN IM – 2000 – 3067, Loyalty Islands, Lifou, 15.7 x 6.4 mm; E. LAGON, Stn. 542, Grand Récif Sud, SL 15.3 mm; F. PLOUVEAL Stn. 1221, SL 15.1 mm; G, H. New Caledonia, EXPÉDITION MONTROUZIER, Touho Stn. 1242, 12.2 x 5.1 mm; I. Radula voucher, New Caledonia, EXPÉDITION MONTROUZIER, Koumac Stn. 1283, SL 12.6 mm (radula—Fig. 12 E, F); J. Protoconch, Loyalty Islands, Lifou, LIFOU 2000, Stn. 1424.