Pisidia dispar (Stimpson, 1858)

Porcellana dispar Stimpson, 1858: 242 (type locality: Port Jackson, Australia); 1907: 190, pl. 23, fig. 3. Polyonyx carinatus Ortmann, 1892: 268, tab. 12, figs. 2, 2e (type locality: Amami-Oshima, Ryukyu Islands). Porcellana rostrata Baker, 1905: 260, pl. 35, figs. 1, 1a, b (type locality: Investigator Strait, South Australia). Pisidia dispar .— Nakasone & Miyake, 1968b: 97, text-fig. 1.— Haig, 1979: 128, figs. 10, 11.

Material examined. New Caledonia. Kuendu Beach, lagoon, 22°23’S, 166°32’E, 31 m, 5 May 1996, coll. B. Richer de Forges, 2 ovig. females CL 2.4, 3.2 mm. Pins Island, lagoon, Aug. 1993, coll. Menou, 1 male CL 3.3 mm. Lagoon, Sep. 1978, coll. C. Vadon, 1 female CL 3.2 mm. Récif du Larégnère, lagoon, 12–16 m, 3 May 1993, 2 male CL 3.4, 3.7 mm, 1 ovig. female CL 3.5 mm. Montrouzier Expedition, Koumac, lagoon, outer reef slope, 20 m, 6 Oct. 1993, 1 female CL 3.0 mm. Montrouzier Expedition, Touho, lagoon, sand, 7 Sep. 1993, 1 male CL 2.0 mm, 1 female CL 2.5 mm. Récif Senez, lagoon, 7 m, 7 Sep. 1992, coll. P. Bouchet, 1 female CL 3.1 mm. Récif Senez, lagoon, 7 m, 7 Sep. 1992, coll. P. Bouchet, 2 male CL 2.3, 2.7 mm, 4 females CL 2.2–3.0mm. Grotte Merlet, lagoon, 20–30 m, 19–21 Jan. 1993, coll. J.-L. Menou, 2 males CL 2.3, 3.0 mm, 2 females CL 2.3, 2.8 mm. Platier de Thio, lagoon, low tide, 1 m, 1 Jul. 1996, coll. B. Richer de Forges, 1 male CL 3.6 mm. Récif Mbere, lagoon, 22°19.9’S, 166°13.2’E, 25–30 m, outer reef slope, 7 Jan. 1993, coll. P. Bouchet, 1 ovig. female CL 2.7 mm.

Remarks. Great sexual dimorphism in the morphology of the chelipeds is known in this species as illustrated by Nakasone & Miyake (1968b, text-fig. 1C–G).

Pisidia variabilis (Yang & Sun, 1985) is closely allied to this species but may be distinguished by the less produced rostrum and meri of the ambulatory legs armed with small spines on the extensor margins (Yang & Sun 2005). Hsieh et al. (1997) recorded P. d i s p a r from Taiwan and illustrated the merus of the first ambularory leg being armed with a single spine on the extensor margin (fig. 31C).

Ortmann (1892) described a new species, Polyonyx carinatus, from Amami-oshima Island of the Ryukyu Islands. Nakasone & Miyake (1969) transferred this species to their new genus Aliaporcellna, but they did not examine the type material. Examination of the syntypes of Polyonyx carinatus by Komai (1999) has revealed that Ortmann’s taxon is conspecific with Pisidia dispar .

Distribution. Northward to Honshu, Japan; southward to temperate Australia, eastwards to Fiji Islands, and westward to Moluccas; littoral to 188 m; under stones and in coral crevices, mussel clumps, and other sheltered habitats (Haig 1979, 1981b).