Clavus devexistriatus, 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 : 44-46

Clavus devexistriatus new species

( Figs. 22 A–C, 24 A, B)

Type material. Holotype: Chesterfield Plateau, CORAIL 2, Stn. DW67, 19°14.9’S, 158°36.9’E, 66 m, MNHN IM–2000–26936. Paratype: Lansdowne–Fairway Banks, Coral Sea, CORAIL 2, Stn. DW28, 20º28.1’S, 160º56.3’E, 78 m ( MNHN IM–2000–26937).

Other new caledonian material examined (total 3 lots, 3 specimens, including type material):

New Caledonia, LAGON, Stn. 933 (1 spm).

Etymology. devexus (sloping downward) + striatus (with fine spiral threads), latin compound adjective.

Distribution. At present known from the Coral Sea and New Caledonia, alive in 66– 100 m.

Diagnosis. Breadth/length 0.45, aperture/total length 0.31; fasciole feeble, base of siphonal canal not indented; anal sinus moderately deeply U-shaped, somewhat constricted; stromboid notch slight; axial ribs forming sharp, somewhat hooked angles slightly above midwhorl, their tips weakly squamiform, in t/s sharply angular, equal in width to their intervals, 11 on penultimate whorl, reaching sutures, but thinner on shoulder slope, anteriorly reaching rostrum; axial ribs not bearing nodules towards their base; a thick hump-like terminal varix ca 0.20 last whorl behind lip. Spiral sculpture very fine on shoulder slope, anteriorly with 12 coarser ridges, plus six rounded ridges on rostrum. Dull, pale brownish, with a band of darker brown below suture. Attains 15.7 mm.

Description. Claviform (breadth/length 0.45, aperture/total 0.31), base obconical; spire turreted, slightly coeloconoid, moderately acute, early whorls with periphery weakly angular, more or less median, later whorls with axial ribs forming a sharp, somewhat squamiform angle slightly above periphery; suture slightly sinuous, base relatively broad, fasciole barely developed, base of siphonal canal truncate, not indented, siphonal canal wide. Outer lip strongly convex, edge weakly crenate, with a shallow stromboid notch; anal sinus moderately deeply Ushaped, adapically sloping, strongly constricted by a peripheral nodule.

Axial ribs forming sharp, adapically hooked angles, their tips squamiform, opisthocline, suture-to-suture, but thin and curved on subsutural slope, in t/s angular with sloping sides, equal in width to their intervals, eight on first teleoconch whorl, 11 on penultimate whorl, anteriorly reaching the rostral lirae; axial ribs not forming nodules towards their base; a thick, rounded terminal varix ca 0.2 whorl behind lip. Spiral sculpture weak but distinct, about 12 anterior to periphery on base, plus about six rounded ridges on rostrum; shoulder slope with fine spiral threads; spiral threads in places undulating and sloping anteriorly.

Protoconch worn and encrusted, cyrtoconoid, evidently ca 2.5 whorls, last whorl with about seven axial riblets.

Dull, pale brown with a zone of darker brown below suture.

Measurements. Holotype 15.7 x 7.0 mm, ap. 4.8 mm.

Radula ( Fig. 24 A, B): Rachidian rather narrow, length twice exceeds width, anterior edge rounded. Teeth with long median cusp and fine side denticles. Lateral teeth broad, arcuate, with 14–15 cusps, 3rd–5th from inner side being the longest and gradually diminishing in length towards outer side, where they evanesce. Marginal teeth relatively long and narrow, with large blade. On anterior edge of the tooth blade constitutes more than 2/3 of teeth length, on posterior edge about 1/3 of tooth length. Blade edges weakly thickened. Accessory limb weak. About 40 rows of teeth.

Remarks. Clavus devexistriatus resembles Clavus squamiferus new species, but bears fine but distinct spiral threads, becoming somewhat oblique in places. Such groups of slanting spiral ridges occur also in some species of Drillia Gray, 1838 (e.g. D. dunkeri (Weinkauff, 1876) and D. siebenrocki (Sturany, 1900) , fide Tippett (2006)).

Figures

FIGURE 22. Clavus devexistriatus n. sp. A, B. Holotype; C. Radula voucher, New Caledonia, LAGON, Stn. 933, SL 12.8 mm (radula—Fig. 24 A, B).

FIGURE 24. Radulae of Clavus devexistriatu s n. sp., C. hylicos n. sp. and C. maestratii n. sp. A, B. Clavus devexistriatus, New Caledonia, LAGON, Stn. 933, SL 12.8 mm (shell—Fig. 22 C); C, D. Clavus hylikos; New Caledonia, EXPÉDITION MONTROUZIER, Touho Stn. 1260, SL 7.5 mm (shell—Fig. 23 D). E, F. Clavus maestratii, EXPÉDITION MONTROUZIER, Koumac Stn. 1309, SL 9.8 mm (shell—Fig. 25 E).