Perotrochus wareni, Anseeuw, Puillandre, Utge & Bouchet, 2015

Anseeuw, Patrick, Puillandre, Nicolas, Utge, José & Bouchet, Philippe, 2015, Perotrochus caledonicus (Gastropoda: Pleurotomariidae) revisited: descriptions of new species from the South-West Pacific, European Journal of Taxonomy 134, pp. 1-23 : 5-8

Perotrochus wareni sp. nov.

urn:lsid:zoobank.org:act:51E7B304-66D2-4AE6-84C0-3A4427203065

Figs 1A , 3 A–F, 4A–J

Etymology

This new species is named in honor of Dr Anders Warén of Naturhistoriska Riksmuseet, Stockholm, in recognition of his lifetime interest in deep-sea exploration and his participation in expeditions around New Caledonia and elsewhere in the South Pacific, many of which yielded specimens used in this paper.

Material examined

73 lots comprising 176 specimens ( Table 1 ).

Type material

Holotype

NEW CALEDONIA: a sequenced specimen, MNHN-IM-2007-36460 .

Paratypes

NEW CALEDONIA: MNHN-IM-2007-34680 ( Fig. 4 A–B); MNHN-IM-2007-34684 ( Fig. 4 C–D); MNHN-IM-2007-34685 ( Fig. 4 E–F); MNHN-IM-2007-36456 ( Fig. 4 G–H); MNHN-IM-2007-36461 ( Fig. 4 I–J).

Type locality

Norfolk Ridge, Munida Bank, 22°59’ S, 168°21’ E, 320–390 m (TERRASSES sta. DW3101).

Description (holotype)

Shell of medium size, solid, thick, general profile rather conical, with weakly convex, rather straightsided whorls, with a diameter a little smaller than its height (H/D ratio = 1.08), numbering 10.5 teleoconch whorls, with a mean spire angle of 65° with weakly impressed suture, whorl surface dull. Protoconch

glassy, rather obtusely depressed. Teleoconch with heavily beaded spiral cords very early on. Dominant

teleoconch sculpture consisting of finely but strongly beaded spiral cords, intersecting less marked axial riblets. Periphery of basal disc crenulated due to a strongly marked spiral cord running at edge of disc. On last whorl, 13 spiral cords above selenizone, 4 spiral cords below, and 2 major cords in the selenizone itself. Slit short, about 1/7 th the circumference of last whorl, situated below midwhorl, and very narrow. Aperture rectangularly depressed. Basal disc rather flat, depressed in its center and sharply edged at its periphery, with a very wide (extending over 40% of base diameter) callus pad which is finely ridged radially. Inside aperture, inner slit lips only partially covered by nacre, leaving a V-shaped area uncovered (approximately 25% of surface of inner slit lip extremity in aperture uncovered by nacre, showing only porcellaneous layer). Nacre coverage thick, no surface sculpture showing through it. Background color yellowish beige, with some faint axial orange-red flammulations, not really arranged into a distinct checker-board pattern; basal disc of same colour, with some faint orange axial flammulation reaching only to basal disc edge. Operculum small, multispiral, circular, light yellowish.

Measurements

Maximum basal diameter (D) 46.75 mm, minimum diameter 43.9 mm. Height (H) 50.27 mm. H/D = 1.08. Length of slit at upper margin 26.7 mm, at lower margin 16.2 mm. Slit width: 1.6 mm; slit length: 1/6.51 th of circumference of last whorl. Weight of empty shell 26.3 g.

Discussion

One of the distinctive shell characters separating Perotrochus wareni sp. nov. from P. caledonicus is the well-marked beading on the teleoconch spiral cords, visible also on the earlier whorls, giving it at first glance its typical pustulose or granular appearance. The intensity of the beading varies between specimens, leading to “heavily beaded”/“very pustulose” specimens and to “weakly beaded” / “light pustulose” specimens, with all different intergrades. This variability may reflect environmental conditions, as the beading intensity is generally stable within one haul / lot and varies between hauls / lots. Leaving aside beading intensity, shell characters are quite stable in P. wareni sp. nov. The general profile of the teleoconch, the outline of the aperture, the selenizone and slit width, and the extension of the callus on the basal disc, all show consistent differences between P. wareni sp. nov., P. caledonicus and P. pseudogranulosus sp. nov. ( Table 2 ). Perotrochus wareni sp. nov. also bears some resemblance to P. gotoi Anseeuw, 1990 , and, in fact, a specimen of the granulated P. “ cfr . caledonicus ” ([i.e., P. wareni sp. nov.) had been used for comparison at the time of its original description ( Anseeuw 1990). Perotrochus wareni sp. nov. can be separated from P. gotoi by its somewhat shorter slit length (1/6.51 th of basal diameter in wareni sp. nov. vs 1/6 th in gotoi ), the larger number of spiral cords on adult specimens, the more irregularly banded checkerboard colour pattern in the area below the selenizone, the heavier and thicker shell (around 60–70% heavier at comparable shell sizes), the less extensive area uncovered by the nacreous layer inside the apertural inner slit lip extremities, and the umbilical callus occupying a much larger surface on the basal disc (45% in P. wareni sp. nov. vs 28% in P. gotoi ). The two species, however, share (also with Mikadotrochus salmianus (Rolle, 1899) the nacreous coverage of the inner slit lips in the aperture, a feature that separates them from Perotrochus caledonicus s.s. and P. pseudogranulosus sp. nov. ( Table 2 , Figs 3–4 , 7 ). Other features, like a deeper, more intense colour pattern on the teleoconch and basal disc, fine microgranulosity on the spiral cords, a thin, light shell, and a more lustrous shell surface, further separate Perotrochus pseudogranulosus sp. nov. from P. wareni sp. nov. ( Table 2 , Figs 3–6 ).

Figures

Fig. 1. Distribution maps of the four species. A. Perotrochus wareni sp. nov. B. Perotrochus deforgesi Métivier, 1990. C. Perotrochus caledonicus Bouchet & Métivier, 1982. D. Perotrochus pseudogranulosus sp. nov. Stations with sequenced specimens in black.

Fig. 3. Perotrochus wareni sp. nov., MNHN-IM-2007-36460, holotype (H = 50.3 mm). A–D. Teleoconch. E. Slit. F. Protoconch.

Fig. 4. Perotrochus wareni sp. nov., paratypes. A–B. MNHN-IM-2007-34680 (H = 28.2 mm). C–D. MNHN-IM-2007-34684 (H = 43.8 mm). E–F. MNHN-IM-2007-34685 (H = 21.5 mm). G–H. MNHN-IM-2007-36456 (H = 55.1 mm). I–J. MNHN-IM-2007-36461 (H = 48.8 mm).

Fig. 7. A–F. Perotrochus caledonicus Bouchet & Métivier, 1982. A–B. MNHN-IM-2000-1262, holotype (H = 31.2 mm). C–D. MNHN-IM-2007-36300 (H = 51.2 mm). E–F. MNHN-IM-2007-36301 (H = 47.5 mm). — G–L. Perotrochus deforgesi Métivier, 1990. G–H. MNHN-IM-2000-1391, holotype (H = 33.9 mm). I–J. MNHN-IM-2007-32062 (H = 33.7 mm). K–L. MNHN-IM-2007-32085 (H = 25.1 mm).