Pleisticanthoides piccardorum, Ng, Peter K. L. & Forges, Bertrand Richer De, 2012

Ng, Peter K. L. & Forges, Bertrand Richer De, 2012, Pleisticanthoides Yokoya, 1933, a valid genus of deep-sea inachid spider crabs (Crustacea: Decapoda: Brachyura: Majoidea), with descriptions of two new species from the Philippines, Papua New Guinea and Vanuatu, Zootaxa 3551, pp. 65-81 : 75-80

Pleisticanthoides piccardorum n. sp.

( Figs. 1 D, 7, 8B, 9C, 10B, 11E–G)

Material examined. Holotype: Ovigerous female (18.6 × 13.6 mm) (MNHN-IU-2012-768), Big Bay, Espiritu Santo I., Vanuatu, station AT 92, 14°59.7'S 166°51.9'E, 722–780 m, coll. SANTO 2006, 13 October 2006.

Paratypes: 1 male (13.1 × 9.9 mm) (with rhizocephalan), 1 damaged male (17.4 × 12.9 mm) (MNHN-IU-2012- 769), Big Bay, Espiritu Santo I., Vanuatu, station AT 89, 14°59.7'S 166°55.3'E, 630–658 m, coll. SANTO 2006, 13 October 2006.— 1 male (20.7 × 16.8 mm) ( ZRC 2012.0909), Big Bay, Espiritu Santo I., Vanuatu, station AT 98, 15°06.6'S 166°50.8'E, 347–394 m, coll. SANTO 2006, 14 October 2006. Additional material: 1 female (16.0 × 22.4 mm) (MNHN-IU-2011-1175), south of Lae, Gulf of Huon, Papua New Guinea, station CP 3630, 06°54’S 147°03’E, 305–307 m, coll. BIOPAPUA 2010, 22 August 2010.—1 ovigerous female (15.7 × 22.7 mm) (MNHN- IU-2011-1895), point southwest of Manus I., Papua New Guinea, station CP 3693, 02°10’S 147°17’E, 300 m, coll. BIOPAPUA 2010, 29 September 2010.

Description. Carapace pyriform; dorsal surface covered by numerous hooked setae, otherwise smooth, without spines, spinules or granules; carapace regions well-defined. Pseudorostral spines short, distinctly diverging; base with strong sharp tooth directed ventrally. Ocular peduncle long, slender; cornea small, round, slightly wider than diameter of peduncle; small blunt spine on upper surface of peduncle. Interantennular spine (= true rostrum) distally bifid. Basal antennal article with 3 blunt spines, one medially on outer margin, 2 distal; urinary article with strong triangular tooth adjacent to prominent green gland. Supraocular eave with 2 short triangular teeth: strong supraocular spine plus longer, curved subhepatic spine; small spine about half length of supraocular spine between subhepatic, supraocular spines. Third maxilliped with segments flattened, covered by long setae; outer border of carpus crenulated. Ambulatory legs long, slender, lined with long, stiff setae. Chelae not inflated, with longer setae on inner side of carpus. Second pereiopod longest; segments with setae arranged in 2 rows along margins. Abdomen with 6 free somites plus telson; sixth somite with distolateral margins expanded, overlapping telson. G1 curved, distinctly C-shaped, distal third dorsolaterally flattened but slightly twisted.

Etymology. The name honors the Piccard family, Auguste Piccard (1884–1962), the inventor of the bathyscaphe, and his son, Jacques Ernest-Jean Piccard (1922–2008), who, together with U.S. Navy officer Don Walsh, were the first men to dive to a record depth of 10,915 m in the Mariana Trench in the Trieste on January 23 1960.

Remarks. Pleisticanthoides piccardorum n. sp. is easily distinguished from P. c a m e ro n i n. sp. by several notable characters. The supraocular tooth of in P. cameroni n. sp. is proportionately larger and stronger ( Figs. 1 C, 8A versus Figs. 1 D, 8B) and the basal antennal article relatively longer and more slender with smaller spines ( Fig. 9A ) than in P. piccardorum n. sp. which has the article stouter with three spines (two distal and one on the outer margin) ( Fig. 9B ). The secondary spine at the base of the pseudorostral spine is directed outwards in P. cameroni n. sp. ( Fig. 1 C) but in P. piccardorum n. sp., it is distinctly directed ventrally ( Fig. 1 D). The G1 of P. piccardorum n. sp. ( Fig. 11 E) is also more strongly bent than that of P. cameroni n. sp. ( Fig. 11 C). In addition, the setae on the pereiopods of P. piccardorum n. sp. are relatively shorter and less stiff ( Fig. 8 B) compared to those of P. c a m e ro n i n. sp., which are longer, stiff and spine-like ( Fig. 8 A).

The base of the longest setae along the ventral margin of the pereiopod meri (especially the second leg) is heavily chitinised and resembles a sharp tubercle. This sharply contrasts with the almost transparent setae. As such, the ventral margin of the merus appears to be lined with a row of short sharp spines ( Fig. 7 B), which is actually not the case.

One male specimen (MNHN-IU-2012-769) was parasitized by a rhizocephalan and as a result had a reduced G1 and a feminised abdomen.

Figures

FIGURE 1. Dorsal views of frontal region showing eyes. A, Pleistacantha cervicornis Ihle & Ihle-Landenberg, 1931, male (20.4 × 16.6 mm) (ZRC), Balicasag, Panglao, Bohol, Philippines, coll. 14 June 2004; B, Pleistacantha oryx Ortmann, 1893, female (30.4 × 18.7 mm) (IOCAS K 87 B- 29), Nanhai, South China Sea, China, 200 m, coll. 18 November 1959; C, Pleisticanthoides cameroni n. sp., male holotype (18.7 × 13.9 mm) (NMCR), Philippines; D, Pleisticanthoides piccardorum n. sp., ovigerous female holotype (18.6 × 13.6 mm) (MNHN-IU- 2012 - 768), Vanuatu.

FIGURE 7. Pleisticanthoides piccardorum n. sp., colour in life, male paratype (20.7 × 16.8 mm) (ZRC 2012.0909), station AT 98, Santo I., Vanuatu. A, overall dorsal view; B, carapace.

FIGURE 8. Overall views. A, Pleisticanthoides cameroni n. sp., male holotype (18.7 × 13.9 mm) (NMCR), Philippines; B, Pleisticanthoides piccardorum n. sp., ovigerous female holotype (18.6 × 13.6 mm) (MNHN-IU- 2012 - 768), Vanuatu.

FIGURE 9. A, B, D, Pleisticanthoides cameroni n. sp., male holotype (18.7 × 13.9 mm) (NMCR), Philippines; C, Pleisticanthoides piccardorum n. sp., ovigerous female holotype (18.6 × 13.6 mm) (MNHN-IU- 2012 - 768), Vanuatu; E, Pleistacantha cervicornis Ihle & Ihle-Landenberg, 1931, male (20.4 × 16.6 mm) (ZRC), Balicasag, Panglao, Bohol, Philippines, coll. 14 June 2004. A, ventral surface of anterior thoracic sternum and male abdomen; C, D left third maxillipeds; B, E, male abdomens.

FIGURE 11. G 1 s. A – D, Pleisticanthoides cameroni n. sp., male holotype (18.7 × 13.9 mm) (NMCR), Philippines; E – G, Pleisticanthoides piccardorum n. sp., male paratype (17.4 × 12.9 mm) (MNHN-IU- 2012 - 769), Vanuatu.