Petrolisthes haswelli Miers, 1884

Osawa, Masayuki, 2007, Porcellanidae (Crustacea: Decapoda: Anomura) from New Caledonia and the Loyalty Islands, Zootaxa 1548, pp. 1-49 : 23-24

Petrolisthes haswelli Miers, 1884

Petrolisthes haswelli Miers, 1884: 269 , pl. 29, fig. A (type locality: Thursday Island, Torres Straits, Queendsland).— Haig, 1979: 123, fig. 4.— Yang & Sun, 1992: 199, figs. 4, 5.— Hsieh et al., 1997: 324, figs. 24E, 27.

Material examined. Type material: Australia. Thursday Island, Torres Straits, Queensland, HMS 'Alert' coll. Dr. Coppinger, Jun. 1881, 1 female CL 13.6 mm, holotype (NHM 1882. 7). Torres Straits, Queendsland, coll. J. B. Jukes, 1845, 2 ovig. females CL 14.2, 14.7 mm, paratypes (NHM 1845. 91). Port Curtis, Facing Island, Queendsland, 23°49’S, 151°22’E, HMS 'Rattlesnake', coll. J. McGillivray, 1850, 1 female CL 13.8 mm, paratype (NHM 1850. 112).

Japan. Iriomote Jima (Koo-Keang-San), Ryukyu Retto, Japan, 24°20' N, 123°50’E, HMS 'Samarang', 1847, 1 male CL 10.3 mm, 1 female CL 13.8 mm, paratypes (NHM1847. 21).

Loyalty Islands. Lifou Island. Atelier LIFOU. Nathalo, intertidal, 27 Nov. 2000, 2 males CL 8.6, 16.7 mm, 1 ovig. female CL 11.4 mm.

Remarks. This species closely resembles P. lamarckii but differs in having the carapace being comparatively more convex and covered with interrupted but distinct striae on the dorsal surface, carpi of the chelipeds each provided with more than four broad teeth on the dorsoflexor margin (usually three teeth in P. l a m a rc k i i), and strong granulation of the chelae (frequently faintly rugose and granular in P. l a m a rc k i i).

Petrolisthes haswelli is also allied to P. borradailei Kropp, 1984 but is distinguished by having a pair of the epibranchial spines on the carapace, carpus of the cheliped armed with three or four spines including a distal projection on the extensor margin (two, rarely three, spines in P. borradailei ), and carpus of the first ambulatory leg usually armed with a small spine on the distal extensor margin.

Miers (1884) cited a specimen of P. haswelli from Koo-Keang-San in the southern Ryukyu Islands, but Haig (1965) compared it with the type and other Australian material and concluded that it should probably be referred to P. lamarckii (also see Haig 1979). However, my re-examination of the type specimens of P. haswelli including two 'Samarang' specimens from Koo-Keang-San (Iriomotejima Island) has revealed that the two specimens are correctly identified as P. haswelli . The specimens from Koo-Keang-San have smaller and more densely distributed, flattened tubercles on the chelae than other specimens, but other characters agree well with those of the specimens examined of P. haswelli . These differences fall into intraspecific variations of this species.

Petrolisthes haswelli can be found in intertidal rocky areas on muddy flats at Iriomotejima Island, although this species seems to be a rather rarely collected porcellanid in the Ryukyu Islands.

Distribution. Australia (Queensland, Northern Territory, and Western Australia), Moluccas, Guangxi Province and Hainan Island in China, Taiwan, and Ryukyu Islands; intertidal, under rocks ( Haig 1979; Hsieh et al. 1997; Yang & Sun 2005). This is the first record of the species from islands in the southwestern Pacific.