Perotrochus pseudogranulosus, 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 : 9-12

Perotrochus pseudogranulosus sp. nov.

urn:lsid:zoobank.org:act:CE972B51-FB50-4C06-B1B2-DD01A6BC737D

Figs 1D , 5 A–F, 6A–J

Etymology

The specific epithet emphasizes the beaded spiral sculpture of the species.

Material examined

40 lots comprising 84 specimens ( Table 1 ).

Type material

Holotype

NEW CALEDONIA: a sequenced specimen, MNHN-IM-2009-7495 .

Paratypes

NEW CALEDONIA: MNHN-IM-2007-32058 ( Fig. 6 A–B); MNHN-IM-2007-32066 ( Fig. 6 C–D); MNHN-IM-2009-7485 ( Fig. 6 E–F); MNHN-IM-2009-7491 ( Fig. 6 G–H); MNHN-IM-2009-7493 ( Fig. 6 I–J).

Type locality

Coral Sea, Capel Bank, 24°45’ S, 159°42’ E, 348–354 m (EBISCO sta. CP2494).

Description (holotype)

Shell of medium size, light, thin, general profile rather conical, with weakly convex to straight-sided whorls with weakly impressed suture, diameter significantly exceeding height (H/D = 0.78), numbering 8 teleoconch whorls, with a mean spire angle of 80°. Protoconch ivory white, depressed. Dominant sculpture of teleoconch consisting of numerous lightly beaded spiral cords, with microsculptural pattern of fine radiating threads, giving the entire whorl surface a shiny metallic luster. On last whorl, 11 spiral cords above selenizone, 7 below and 3 major cords in the selenizone itself. Slit long, about 1/5 th the circumference of the last whorl, situated below midwhorl, and rather narrow. Aperture depressed. Basal disc rather flattened, with angular edge, with a relatively narrow (extending over 30% of base diameter) light nacreous callus pad which is finely ridged radially and ends in a raised porcellaneous edge. Inside the aperture inner slit lips nearly completely covered by nacre, leaving a narrow area (approximately 15% of the surface) parallel to the inner slit lips uncovered, showing only porcellaneous layer. Background colour yellowish beige, with intense reddish crimson colour markings arranged in very regular checkerboard pattern, overall reinforcing color intensity; basal disc showing some contrasting reddish crimson flammulations, particularly visible at its periphery, and more yellowish tan towards the center. Operculum small, multispiral, circular, light yellowish (fallen off/missing in holotype).

Measurements

Maximum basal diameter (D) 64.9 mm, minimum diameter 59.1 mm. Height (H) 50.7 mm. H/D = 0.78. Depth of slit at upper margin 42.1 mm, depth of slit at lower margin 26.9 mm. Slit width 3.1 mm. Slit length: 1/5.64 th of circumference of last whorl. Weight of empty shell 42.6 g.

Discussion

Perotrochus pseudogranulosus sp. nov. most closely resembles P. caledonicus ( Fig. 7 ) at first glance, but is distinguished by its more conical and higher shell, a more flattened basal disc profile and a more intense and regular checkerboard colour pattern and more lustrous shell surface. It differs from P. wareni sp.

nov. by its weakly beaded spiral cords with a microsculpture of fine radiating threads, its more intensely

marked checkerboard colour pattern, with metallic luster, a much longer slit and a much smaller callus pad area on the basal disc. Finally, it differs from P. deforgesi ( Fig. 7 ), the only other species occurring in the Coral Sea, by its general outline which is distinctly higher conical, its thin shell, its more intense checkerboard colour markings, its less granular spiral cords and smaller callus pad coverage on the basal disc.

Some specimens of P. pseudogranulosus sp. nov. have over the years turned up in the shell trade as “ P. cfr . caledonicus ”, supposedly originating from NW Australia or even from the South China Sea ( Anseeuw & Goto 1996). However, based on the lack of precise and trustworthy locality data, the lack of more recent confirmation of those alleged findings and, most of all, the general unavailability of such material for study, we reject these localities as intentionally or unintentionally unproven and unverifiable.

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. 5. Perotrochus pseudogranulosus sp. nov., MNHN-IM-2009-7495, holotype (H = 54.3 mm). A–D. Teleoconch. E. Slit. F. Protoconch.

Fig. 6. Perotrochus pseudogranulosus sp. nov., paratypes. A–B. MNHN-IM-2007-32058 (H = 53 mm). C–D. MNHN-IM-2007-32066 (H = 29.8 mm). E–F. MNHN-IM-2009-7485 (H = 42.1 mm). G–H. MNHN-IM-2009-7491 (H = 36 mm). I–J. MNHN-IM-2009-7493 (H = 32.1 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).