Cryptogemma powelli, Zaharias & Kantor & Fedosov & Criscione & Hallan & Kano & Bardin & Puillandre, 2020

CRYPTOGEMMA POWELLI View in CoL SP. NOV.

( FIG. 11)

urn:lsid:zoobank.org:act:EC0DAF2A-AD02-4D9D-8970-B49A70385A0A

Type material: Holotype MNHN-IM-2013-68787; paratype 1, MNHN-IM-2007-40795; paratype 2, MNHN-IM-2007-40765; all live collected and processed for DNA extraction.

Type locality: New Caledonia, south-west of Ile des Pins , 22°48′S, 167°15′E, 449–465 m depth, sand and debris (Expedition KANACONO, st. DW4697) GoogleMaps .

Etymology: Named after New Zealand malacologist Arthur William Baden Powell CBE (1901–1987), who contributed enormously to the systematics of Conoidea and, in particular, who revised the family Turridae in 1964 and described several species of Cryptogemma .

Description (holotype): Shell narrowly fusiform, with high spire and medium-long siphonal canal. Protoconch conical, eroded, with a diameter of 1.125 mm, of about four convex whorls. Teleoconch of nine whorls; suture shallow, impressed. Shell height 38 mm, aperture height 10.9 mm and shell diameter 12.5 mm. Whorls strongly shouldered, with slightly concave shoulder slope, very weakly convex, nearly cylindrical periphery. Spiral sculpture of fine, broadly spaced, wavy, subequal spiral cords on subsutural ramp, ten on last whorl, uppermost being much more pronounced than the others, coloured light orange-brown. Sinus cord strongly gemmate, with gemmules clearly bisected (39 on the body whorl). Spiral cords becoming thicker on whorl periphery, sometimes nodulose, some notably wider than others. Axial sculpture of fine growth lines. Last whorl shortly constricted to long siphonal canal, with 32 cords below the sinus, of which ~20 on canal. Aperture irregular oval, outer lip thin, simple. Anal sinus moderately deep, U-shaped. Shell colour straw-yellow, subsutural cord orange-brown, gemmae slightly lighter than background.

Radula medium long, ~ 3.1 mm in length (0.28 of AL), composed of 75 transverse rows of teeth. Marginal teeth 129–135 µm long (mean 133 µm, N = 5 or 1.22% of AL), duplex. Anterior (inner) one-third of tooth length solid, lanceolate in dorsal view, in posterior part major and accessory limbs broadly bifurcating; accessory limb with clear constriction at half tooth length, thin, about half the length and width of the major limb. Central formation with medium long and medium broad sharp carinated cusp and lateral flaps with distinct posterior and posterolateral margins. Flaps not completely fused with cusp ( Fig. 7H).

Remarks: This species corresponds to PSH 15 in the study by Puillandre et al. (2012). Cryptogemma powelli exhibits similar intraspecific variation in shell shape to that of its congeners, based on its convex hull area ( Fig. 1). Studied specimens vary in shades of shell colour, from light yellowish to light orange, occasionally with a patchy pattern. In terms of both size and shape, C. powelli can, in some cases, be undistinguishable from C. unilineata ( Fig. 1). The morphometric analysis shows considerable overlap of the measured shell features between the two species, with the main distinction between them expressed by the second axis. Interpretation of this result suggests that the C. powelli on average possesses a more concave curvature of the outer aperture lip, in comparison to C. unilineata . Besides, distinction of C. powelli and C. unilineata mostly relies on the degree of pronunciation of the subsutural cord; it is typically not significantly stronger than the succeeding cords in the former species, but is always thick and gemmate in the latter. However, the subsutural cord is thicker in younger specimens, rendering the distinction of juvenile C. powelli and C. unilineata specimens problematic.

List of COI diagnostic sites (position: character state): [112: G; 322: T; 433: A].

Distribution: The confirmed distribution of this species based on sequenced specimens ranges from the Indian Ocean to the central Pacific ( Fig. 4F), from a depth of ~400 to ~ 600 m.