Clavus formosus (Reeve, 1846)

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 : 34-35

Clavus formosus (Reeve, 1846)

( Figs. 12 G, H, 16 A–F)

Pleurotoma tessellata Reeve 1846 (non Clavatula tessellata Hinds, 1843 ): pl. 36, sp. 331. Pleurotoma formosa Reeve 1846 (substitute name): errata.

Other references.

Drillia (Clavus) formosa ; Boettger 1895: 8; Melvill & Standen 1897: 397. Clavus formosus ; Dautzenberg & Bouge 1933: 95.

Clavus (Tylotia) pica (non Reeve, 1843): Hasegawa et al. 2000: 621, pl. 309, fig. 13.

Type data. Two syntypes NHMUK 19631062; length 12.9 mm (lip broken), other 13.9 x 5.5 mm. Type loc.: Capul Island, Philippines.

New caledonian material examined (total 13 lots, 43 spms):

New Caledonia, EXPÉDITION MONTROUZIER, Koumac Stn. 1316 (5 spms); Touho Stn. 1271 (21 spms);

LAGON, Stns. 412 (1 spm), 483 (1 spm), 899 (1 spm), 1180 (1 spm).

Loyalty Islands, Lifou: LIFOU 2000, Stns. 1422 (2 spms), 1429 (2 spms), 1432 (1 spm), 1434 (2 spms), 1454 (1 spm), 1457 (4 spms).

Distribution. Amami Islands and Philippines to New Caledonia, Loyalty Islands, Society and Tuamotu Islands, and west to Sri Lanka, 3 to 53 m, sandy gravel and sediment, in our material confirmed live to ca 30 m.

Description. Claviform, asymmetrical, somewhat pupoid (last two whorls somewhat similar in width), proportions slightly variable (breadth/length 0.33–0.42, aperture/total length 0.34–0.40), aperture somewhat linear, curved to left basally, left side of base concave, without trace of fasciole, slightly obliquely truncate, shallowly indented. Outer lip slightly alate, moderately convex in side-view; anal sinus linguiform, directed slightly adapically, constricted by a more or less strong nodule; stromboid notch shallow to deep.

Surface glossy, rendered somewhat silky by microsculpture. Subsutural region concave, adpressed against previous whorl, concavity occupying about half whorl on early whorls, about 0.3 on penultimate whorl. Axial ribs slightly arcuate, opisthocline, forming a weak, sloping shoulder, initially suture-to-suture, although indented by subsutural concavity, becoming feeble or absent below suture on penultimate whorl, but reaching base of rostrum, in t/s steeply angular, slightly wider than intervals; 9–12 on penultimate whorl. Outer lip preceded (about a quarterwhorl back) by a broad, fairly high, rounded varix. No basal granules or vermiculations. Base of last whorl with 5–7 somewhat declivous spiral ridges. Microsculpture of dense collabral threads and finer spiral ones (the latter visible mainly below suture).

White with irregularly arranged, vivid brownish-orange blotches, which may show traces of several rows of pale spots, dark blotches forming a transverse band on back of last whorl, splitting into two behind lip, which show through to interior of otherwise white aperture.

Protoconch papilliform, of two smooth whorls, breadth 0.57–0.63 mm.

Measurements. Largest and smallest New Caledonian examples: 14.6 x 4.8 mm and 9.3 x 3.9 mm, respectively.

Radula ( Fig. 12 G, H): Rachidian narrow, length exceeds width, anterior edge rounded. Teeth with strong median cusp and fine side denticles that are shorter than tooth base. Posterior edge of tooth base rounded. Lateral teeth medium broad, arcuate, with 12 cusps, 2nd–4th from inner side being the longest and gradually diminishing in length towards outer side, where they evanesce. Marginal teeth long and narrow, with slightly broader short blade. On anterior edge of the tooth blade constitutes 1/2 of teeth length, on posterior edge about 1/5 of tooth length. Blade edges very weakly thickened. Accessory limb not pronounced. About 35 rows of teeth

Remarks. A single specimen from LIFOU 2000 station 1434 (Baie du Santal, in front of ilot Huca Hutighé, hard bottom in 5–20 m) ( Fig. 16 D–E) may represent an undescribed species, but in the absence of further samples is here treated as an extreme form of Clavus formosus . It differs in proportions that are difficult to quantify, having a shorter base, a somewhat wider subsutural concavity and slightly more nodiform axial ribs, rendering the whorls almost pagodiform.

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 16. Clavus formosus (Reeve, 1846). A. Pleurotoma formosa, syntype, NHMUK 19631862, Philippines, Capul Is., SL 12.0 mm; B, C. Loyalty Islands, Lifou, LIFOU 2000, Stn. 1454, 13.4 x 5.0 mm; D, E. Narrow form, Loyalty Islands, Lifou, LIFOU 2000, Stn. 1434, 9.4 x 3.5 mm; F. Radula voucher, Loyalty Islands, Lifou, LIFOU 2000, Stn. 1457, SL 10.1 mm (radula—Fig. 12 G, H).