Bull. Natl. Mus. Nat. Sci., Ser. A, Suppl. 3, pp. 137–156, March 22, 2009 Two New Species of the Hermit Crab Genus Pagurixus (Decapoda: Anomura: Paguridae) from the Western Pacific Tomoyuki Komai1 and Junji Okuno2 1 Natural History Museum and Institute, Chiba, 955–2 Aoba-cho, Chuo-ku, Chiba, 260–8682 Japan e-mail: [email protected] 2 Coastal Branch of Natural History Museum and Institute, Chiba, 123 Yoshio, Katsuura, Chiba, 299–5242 Japan e-mail: [email protected] Abstract Two new species of the pagurid hermit crab genus Pagurixus Melin, 1939 are described and illustrated. Pagurixus purpureus sp. nov., known from Japan and Papua New Guinea, is mor- phologically similar to P. boninensis (Melin, 1939), P. paulayi Komai and Osawa, 2006, and P. ruber Komai and Osawa, 2006. Pagurixus acanthocarpus sp. nov., so far restricted to Japanese wa- ters, appears close to P. fasciatus Komai and Myorin, 2005, P. handrecki Gunn and Morgan, 1992, P. nanus Komai and Takada, 2006, and P. dissimilis Osawa and Komai, 2007. Distinguishing char- acters between respective new species and their allies are discussed. Key words : Decapoda, Anomura, Paguridae, Pagurixus, new species, Japan, New Guinea. The pagurid hermit crab genus Pagurixus scribed. The first, P. purpureus sp. nov., appears Melin, 1939 is widespread in tropical to warm closely related to P. boninensis (Melin, 1939), P. temperate waters in the Indo-Pacific regions. paulayi Komai and Osawa, 2006 and P. ruber Presently, 27 species are known in the genus Komai and Osawa, 2006, all referred to the P. (McLaughlin and Haig, 1984; Gunn and Morgan, boninensis species group (cf. Komai and Osawa, 1992; Morgan, 1993; Komai and Asakura, 1995; 2006). The second, P. acanthocarpus sp. nov., be- de Saint Laurent and McLaughlin, 2000; Komai longing to the P. anceps group (cf. Komai and and Myorin, 2005; Komai, 2006; Komai and Osawa, 2006), appears morphologically similar Osawa, 2006, 2007; Komai and Takada, 2006; to P. fasciatus Komai and Myorin, 2005, P. han- Osawa et al., 2006; Osawa and Komai, 2007), of drecki Gunn and Morgan, 1992, P. nanus Komai which 14 species have been described in the last and Takada, 2006, and P. dissimilis Osawa and eight years. Many of the known species inhabit Komai, 2007. Affinities of these two new species shallow sublittoral reefs where only divers are discussed in detail. Descriptions of the col- equipped with SCUBA are accessible. oration in life, which is known to be species spe- During ongoing studies on the sublittoral her- cific in the genus, are also provided for both mit crab fauna in Japan, conducted by us, a num- species. ber of undescribed species or poorly known The type specimens of the new species are de- species have been found, amongst them two un- posited in the National Museum of Nature and described species of Pagurixus. Furthermore, ex- Science, Tokyo (NSMT), the Natural History amination of abundant material from various Museum and Institute, Chiba (CBM), Coastal western Pacific localities, kindly made available Branch of Natural History Museum and Institute, for study by Dr. Gustav Paulay of the Florida Chiba, Katsuura (CMNH), and the Florida Muse- Museum of Natural History, University of Flori- um of Natural History, University of Florida, da, has resulted the finding of one of the two un- Gainesville (UF). The shield length, abbreviated described species also in Papua New Guinea. In as SL, is measured from the tip of rostrum to the the present paper the two new species are de- midpoint of posterior margin of the shield. Ter- 138 T. Komai and J. Okuno minology used in the description follows each with submarginal spinule. McLaughlin (2003), with the exceptions of num- Ocular peduncles (Fig. 1A) moderately long, bered thoracic sternites and pleon for abdomen. relatively slender, 0.60–0.70 length of shield, each with row of tufts of short setae on dorsal Taxonomy surface mesially; corneas slightly dilated, corneal width 0.26–0.38 of peduncular length; basal part Genus Pagurixus Melin, 1939 somewhat inflated, slightly broader than corneal Pagurixus boninensis species group width. Ocular acicles subtriangular or subovate, each with small submarginal spine distally. Pagurixus purpureus sp. nov. Antennular peduncles (Fig. 1A) overreaching [New Japanese name: Sumire-hime-hon-yadokari] distal corneal margins by 0.30–0.50 lengths of (Figs. 1–4; 9A, B) ultimate segments. Ultimate segment with tufts of long setae at dorsolateral distal angle; ventral Material examined. Holotype: NSMT-Cr surface with 2 longitudinal rows of setae, con- 19740, male (SL 3.4 mm), Issoh, Yakushima Is- sisting of mixture of short and long setae in distal land, Ohsumi Islands, 20 m, 11 January 2007, half (Fig. 1B). Basal segment with small lateral SCUBA diving, coll. Shigeru Harazaki. spine on statocyst lobe. Ventral flagellum with Paratypes: Japan. CMNH-ZC 2251, 1 female row of numerous long setae on lateral and mesial (SL 2.1 mm), Akino-hama, Izu-Oshima Island, margins. Izu Islands, 4 m, 15 May 2005, SCUBA diving, Antennal peduncles (Fig. 1A) overreaching coll. Hirohito Arima; CMNH-ZC 2252, 1 male distal corneal margins by 0.30 lengths of fifth (SL 2.1 mm), CMNH-ZC 2253, 1 female (SL segments. Second segment with tiny spinule at 2.3 mm), same locality, 4 m, 2 June 2005, SCUBA dorsomesial distal angle; laterodistal projection diving, coll. H. Arima; NSMT-Cr 19859, 1 fe- short, not reaching midlength of fourth segment, male (SL 2.3 mm), Kashiwa-jima Island, Ohtsu- terminating in simple or bifid spine. First seg- ki, Kochi Prefecture, 3 m, 10 June 2005, SCUBA ment with small laterodistal spine; ventromesial diving, coll. Naoki Nishimura; CBM-ZC 9560, 2 distal margin produced, unarmed or with spinule females (SL 2.0, 2.3 mm), same locality, subtidal, just lateral to antennal gland opening. Antennal SCUBA diving, coll. Eiji Myorin. Papua New acicle moderately long, arcuate, terminating in Guinea. UF 5398, 1 male (SL 2.4 mm), 4 oviger- slender spine, overreaching base of cornea but ous females (SL 1.7–2.1 mm), “Brooker Chan- not reaching distal corneal margin, mesial margin nel” in Calvados Channel, Milne Bay Province, with row of sparse stiff setae. Flagellum moder- Louisiade Archipalago, 11°03.09ЈS, 152°28.62ЈE, ately long, exceeding 4.00 length of shield. 5–10 m, 1 June 1998, coll. Gustav Paulay. Third maxilliped moderately stout; ischium Non-type. CMNH-ZC 1881, 1 young male (SL with well-developed crista dentata and 1 accesso- 1.2 mm), Akinohama, Izu-Oshima Island, Izu ry tooth. Islands, 13 m, 20 March 2005, SCUBA diving, Right cheliped of males (Figs. 2A, B, 3A) not coll. H. Arima. particularly elongate, moderately stout, distinctly Description. Shield (Fig. 1A) 1.00–1.15 times longer than left cheliped. Chela subovate in dor- longer than broad; anterior margin between ros- sal view, 1.80–2.10 times longer than broad. trum and lateral projections concave; anterolater- Dactylus distinctly shorter than palm; dorsome- al margins sloping; dorsal surface weakly con- sial margin not delimited; surfaces microscopi- vex, with few tufts of short setae laterally. Ros- cally finely granular; cutting edge with row of trum triangular, not reaching level of midlength small calcareous teeth in proximal 0.75 and row of ocular acicles, moderately broad, terminating of small corneous teeth in distal 0.25, terminat- acutely. Lateral projections slightly produced, ing in small corneous or calcareous claw. Palm Two new species of Pagurixus from the western Pacific 139 Fig. 1. Pagurixus purpureus sp. nov., holotype, male (SL 3.4mm), NSMT-Cr 19740. A, shield and cephalic ap- pendages, dorsal view; B, ultimate segment and ventral flagellum of left antennular peduncle, ventral view; C, left fourth pereopod, lateral view; D, right fourth pereopod, lateral view; E, sixth thoracic sternite, ventral view; F, coxae of fifth pereopods and eighth thoracic sternite, ventral view; G, telson, dorsal view. Scale bars: 1 mm for A; 0.5 mm for B–G. 140 T. Komai and J. Okuno Fig. 2. Pagurixus purpureus sp. nov., holotype, male (SL 3.4mm), NSMT-Cr 19740. A, right cheliped, mesial view; B, same, lateral view; C, left cheliped, mesial view; D, same, lateral view. Scale bar: 1 mm. Two new species of Pagurixus from the western Pacific 141 slightly longer than carpus; convex dorsal surface gin faintly delimited by low of small, low gran- microscopically granular, with small but conspic- ules extending onto fixed finger. Cutting edge of uous spine at proximomesial angle; dorsolateral fixed finger with row of small blunt calcareous and dorsomesial margins not delimited; lateral, teeth in proximal 0.80 and row of small corneous mesial and ventral surfaces minutely granular or teeth in distal 0.20, terminating in small corneous nearly smooth, and occasionally with some tufts claw. Carpus 1.30–1.80 times longer than broad, of short setae on ventral surface. Cutting edge of subequal in length to merus; dorsal surface with fixed finger with row of tiny calcareous teeth and 2 rows of moderately large spines mesially and with 1 moderately large, blunt calcareous tooth with row of tiny tubercles laterally, dorsodistal proximal to midlength, terminating in small cal- margin with few small spines; lateral and mesial careous claw. Carpus 1.50–1.70 times longer surfaces coarsely granular, former nearly perpen- than broad; dorsal surface granular (granules dicular, without longitudinal ridge, latter with strongest mesially), with few small spines adja- several stiff setae directed mesially; ventrolateral cent to dorsodistal margin and with 2 rows