RAFFLES BULLETIN OF ZOOLOGY 2014 RAFFLES BULLETIN OF ZOOLOGY Supplement No. 30: 301–304 Date of publication: 25 December 2014 http://zoobank.org/urn:lsid:zoobank.org:pub:98A83F93-D96E-4527-ACBC-0BD70AC8E82A On the crabs of the genus Pseudozius Dana, 1851 (Crustacea: Brachyura: Pseudoziidae) from Christmas Island and the Cocos (Keeling) Islands Jose Christopher E. Mendoza1* & Peter K. L. Ng1,2 Abstract. Recent marine surveys in Christmas Island and the Cocos (Keeling) Islands yielded two species of Pseudozius Dana, 1851. Pseudozius caystrus (Adams & White, 1849) is briely treated. Pseudozius paciicus Balss, 1938, is recorded for the irst time from Christmas Island and the Indian Ocean. Key words. Decapoda, Pseudozioidea, Pseudozius, Indian Ocean, Christmas Island the actual specimens may vary only in the year-related station preix, but not the actual number (e.g., the ield label accompanying a specimen from stn CI2-09, may have been written as “CI-09-2011”, that is, station #09 in Christmas Island, collected in the year 2011). A detailed account of the stations is provided by Tan et al. (2014). INTRODUCTION The Indo-Paciic genus Pseudozius Dana, 1851 (Brachyura: Pseudozioidea) is represented by three species: Pseudozius caystrus (Adams & White, 1849), the type species, P. inornatus Dana, 1852, and P. paciicus Balss, 1938 (viz. Guinot, 1968; Ng & Wang, 1994; Ng et al., 2008). Two species (P. caystrus and P. paciicus) were collected by the recent marine surveys conducted at Christmas Island and the Cocos (Keeling) Islands in 2010–2012 and are treated in this paper. The marine surveys were organised by the Rafles Museum of Biodiversity Research (Singapore) and the Queensland Museum (Brisbane), with support from the Australian authorities, particularly the Christmas Island Park Service. SYSTEMATIC ACCOUNT Superfamily PSEUDOZIOIDEA Alcock, 1898 Family PSEUDOZIIDAE Alcock, 1898 Pseudozius caystrus (Adams & White, 1849) (Fig. 1) Panopeus caystrus Adams & White, 1849: 42, pl. 9 ig. 2 Pseudozius planus Dana, 1852a: 81; 1852b: 233; 1855: pl. 13 ig. 6 Pseudozius microphthalmus Stimpson, 1858: 35 Pseudozius caystrus, Ward, 1934: 23; Tweedie, 1950: 123; Guinot, 1968: 330 (discussion); 1971: 1077; Serène, 1984: 313, igs. 242, 243, pl. 48 ig. B; Garth et al., 1987: 246, 259; Ng & Wang, 1994: 86, igs. 1–8; Morgan, 2000: 122 (table); Davie, 2002: 203; Ng et al., 2008: 180 (list) All material examined are deposited in the Zoological Reference Collection (ZRC) of the Lee Kong Chian Natural History Museum (formerly Rafles Museum of Biodiversity Research), National University of Singapore. Measurements are shown as maximum carapace width (CW) by median carapace length (CL), in millimeters. The following abbreviations are used: I./Is. – island/islands, respectively; juv. – juvenile; ovig. – ovigerous; and stn – station. Material examined. Christmas I.: 9 ♂, 9.1 × 5.6 mm – 16.3 × 10.1 mm, 5 ♀ (2 ovig.), 9.3 × 5.7 mm – 12.8 × 7.5 mm, 6 juv., not measured (ZRC), stn CI1-09; 1 ♂, 11.0 × 6.6 mm (ZRC), stn CI1-20[78]; 1 ♂, 21.3 × 12.8 mm, 3 ♀, 19.7 × 11.9 mm – 22.6 × 13.4 mm (ZRC), 11 ♂, 8.2 × 5.0 mm – 21.5 × 12.9 mm, 15 ♀, 8.8 × 5.4 mm – 22.2 × 13.3 mm (ZRC), stn CI2-03; 1 ♂, 12.3 × 7.4 mm, 4 ♀, 9.0 × 5.4 mm – 18.2 × 11.2 mm (ZRC), stn CI2-17; 1 ♂, 14.0 × 8.3 mm (ZRC), 1 ♂, 21.2 × 12.8 mm (ZRC), 1 ♀, 20.1 × 12.1 mm (ZRC), 1 ♀, 20.8 × 12.6 mm, 1 ♀, 24.0 × 13.6 mm, stn CI3-13. Cocos (Keeling) Is.: 1 ♂, 16.6× 10.2 mm (ZRC), 1 ♂, 19.6 × 11.6 mm, 1 ♀, 16.5 × 10.1 mm (ZRC), stn CK1-08. For simplicity and uniformity, we use the alpha-numeric codes beginning with “CI1”, “CI2”, and “CI3” to denote Christmas Island stations for the three consecutive trips in 2010, 2011 and 2012, respectively. Likewise, “CK1” and “CK2” are used for Cocos (Keeling) stations for the years 2011 and 2012, respectively. Field labels accompanying 1 Department of Biological Sciences, Faculty of Science, National University of Singapore, 14 Science Drive 4, 117543 Singapore; Email: jcmendoza@nus.edu.sg (*corresponding author JCEM) 2 Lee Kong Chian Natural History Museum, Faculty of Science National University of Singapore, 6 Science Drive 2, 117546 Singapore Remarks. Ng & Wang (1994) provided a detailed and extensive discussion of the somewhat convoluted taxonomy of Pseudozius caystrus (type locality: “Eastern seas”, viz. © National University of Singapore ISSN 2345-7600 (electronic) | ISSN 0217-2445 (print) 301 Mendoza & Ng: Pseudozius from Christmas and Cocos (Keeling) islands Pseudozius paciicus Balss, 1938 (Figs. 2, 3) Adams & White, 1849). They also stabilised the species by formally selecting a lectotype from among the syntypes examined by Adams & White (1849), and, in the process, established both Panopeus caystrus Adams & White, 1849, and Pseudozius planus Dana, 1852a, as objective synonyms. Furthermore, they considered Pseudozius microphthalmus Stimpson, 1858, as a junior subjective synonym of P. caystrus. Ng & Wang (1994: igs. 1–8) also provided several detailed line drawings of the lectotype male and paralectotype female, as well as of specimens collected from Taiwan and Christmas Island. ?Pseudozius inornatus, Dana, 1852b: 235; 1855: pl. 13 ig. 8a, b. Not Pseudozius inornatus Dana, 1852 Pseudozius paciicus Balss, 1938: 64, pl. 2 ig. 5; Guinot, 1968: 330 (discussion), ig. 12a, b; 1971: 1077; Garth et al., 1987: 246, 259; Ng & Wang, 1994: ig. 9a, b (corrected); Ng et al., 2008: 180 (list) Material examined. Christmas I.: 1 ♀, 6.4 × 3.9 mm (ZRC) stn. CI1-13(09), 1 juv. 3.6 × 2.4 mm (ZRC), stn. CI1-13(03); 1 ♂, 7.1 × 4.5 mm (ZRC), stn. CI1-13(18); 1 ♂, 8.7 × 5.4 mm (ZRC), stn. CI1-13(21); 1 ♀, 8.0 × 5.0 mm (ZRC), stn. CI1-31(179); 1 ♂, 7.2 × 4.7 mm (ZRC), stn. CI2-09(039); 1♂, 4.9 × 3.1 mm (ZRC), stn. CI2-13(05); 1 ♂, 11.1 × 7.0 mm, 1 ovig. ♀, 12.3 × 7.3 mm (ZRC), stn. CI2-17(074); 2 ♂, 9.4 × 5.9 mm, 10.1 × 6.4 mm, 3 ♀, 7.9 × 5.0 mm – 9.0 × 5.6 mm (ZRC), stn. CI2-17; 1 ♀, 10.6 × 6.8 mm, 1 ovig. ♀, 10.9 × 6.8 mm (ZRC), stn. CI2-22. Colour photographs of this species are provided here (Fig. 1) to show the variation in the live colouration of the specimens found on Christmas Island, which is also similar to that observed in the specimens from Cocos (Keeling) Islands. This species is widely distributed in the Indo-Paciic region (viz. Ng & Wang, 1994), including Christmas Island (Ward, 1934; Ng & Wang, 1994; Morgan, 2000) and the Cocos (Keeling) Islands (Tweedie, 1950), where it is one of the commonest crabs inhabiting the upper to middle intertidal zone. Fig. 1. Live colouration. Pseudozius caystrus (Adams & White, 1849): A, 1 ♂, 14.0 × 8.3 mm (ZRC), stn CI3-13; B, 1 ♂, 11.0 × 6.6 mm (ZRC), stn CI1-20(78); C, 1 ♀, 20.1 × 12.1 mm (ZRC), stn CI3-13; D, 1 ♀, 20.8 × 12.6 mm (ZRC), stn CI3-13. 302 RAFFLES BULLETIN OF ZOOLOGY 2014 Fig. 2. Live colouration. Pseudozius paciicus Balss, 1938: A, 1♂, 4.9 × 3.1 mm (ZRC), stn. CI2-13(05); B, 1 ♂, 7.2 × 4.7 mm (ZRC), stn. CI2-09(039); C, 1 ♂, 7.1 × 4.5 mm (ZRC), stn. CI1-13(18); D, 1 ♂, 11.1 × 7.0 mm (ZRC), stn. CI2-17(074). Remarks. Pseudozius paciicus was originally described by Balss (1938) from Jaluit, in the Marshall Islands. The description and photographs provided by Balss (1938: 64, pl. 2 ig. 5) match the present specimens from Christmas Island. A igure of the G1 provided by Guinot (1968: ig. 12), who studied the type material deposited in the Munich Museum, further conirms their identity. The greatly lared, funnelshaped distal tip of the G1 (Fig. 3), described by Guinot (1968: 331) as “entouré d’un lobe formant un sorte de collerette”, distinguishes this species from its congeners, P. caystrus and P. inornatus, which have the G1 much narrower distally (cf. Guinot, 1968: igs. 13, 14; Ng & Wang, 1994: igs. 1c–e, 4b–e, g, h, 8). The live colouration of P. paciicus is also recorded here for the irst time (Fig. 2). The pattern on the carapace agrees with the illustration by Dana (1855: pl. 13 ig. 8a, b) of a specimen collected from Charlotte’s Island (Kingsmill Group), but which was lost in the shipwreck of the USS Peacock. Dana (1852b: 235) tentatively identiied this specimen as a species he was describing at the time, Pseudozius inornatus. Subsequently, however, Balss (1938) considered this particular specimen as conspeciic with a new species of Pseudozius he was describing, P. paciicus, and listed it in the synonymy for this species. Fig. 3. Left G1. Pseudozius paciicus Balss, 1938: A, B, 1 ♂, 4.9 × 3.1 mm (ZRC), stn. CI2-13(05), C, 1 ♂, 11.1 × 7.0 mm (ZRC), stn. CI2-17(074). 303 Mendoza & Ng: Pseudozius from Christmas and Cocos (Keeling) islands This is the irst record of P. paciicus outside of the Marshall Islands (cf. Balss, 1938; Garth et al., 1987), and also the irst such record in the Indian Ocean. In Christmas Island, it was collected among pebbles and rocks in the intertidal zone, like P. caystrus, but was relatively less common and less conspicuous. This species has not been found on Cocos (Keeling) Islands thus far. Dana JD (1855) Crustacea. Atlas. United States Exploring Expedition. During the years 1838, 1839, 1840, 1841, 1842. Under the command of Charles Wilkes, U.S.N. C. Sherman, Philadelphia, pls. 1–96. Davie PJF (2002) Crustacea: Malacostraca: Eucarida (Part 2): Decapoda – Anomura, Brachyura. In: Wells A & Houston WWK (eds.) Zoological Catalogue of Australia, Vol. 19.3B. CSIRO Publishing, Melbourne, xiv + 641 pp. Garth JS, Haig J & Knudsen JW (1987) Crustacea Decapoda (Brachyura and Anomura) of Eniwetak Atoll. In: Devaney DM, Reese ES, Burch BL & Helfrich P (eds.) The Natural History of Eniwetak Atoll. Vol. 2. Biogeography and Systematics. U.S. Department of Energy, Ofice of Scientiic and Technical Information, Oak Ridge, Tennesse, pp. 235–261. Guinot D (1968) Recherches préliminaires sur les groupements naturels chez les Crustacés Décapodes Brachyoures. VI. Les Carpilinae. Bulletin du Muséum national d’Histoire naturelle, 2e sér., 40(2): 320–334. Guinot D (1971) Recherches préliminaires sur les groupements naturels chez les Crustacés Décapodes Brachyoures. VIII. Synthèse et bibliographie. Bulletin du Muséum national d’Histoire naturelle, 2e sér., 42(5): 1063–1090. Morgan GJ (2000) Decapod Crustacea of Christmas Island. In: Berry PF & Wells FE (eds.) Survey of the Marine Fauna of the Montebello Islands, Western Australia and Christmas Island, Indian Ocean. Records of the Western Australian Museum, Supplement 59: 117–123. Ng PKL, Guinot D & Davie PJF (2008) Systema Brachyurorum: Part I. An annotated checklist of extant brachyuran crabs of the world. Rafles Bulletin of Zoology, Supplement 17: 1–286. Ng PKL & Wang CH (1994) Notes on the enigmatic genus Pseudozius Dana, 1851 (Crustacea, Decapoda, Brachyura). Journal of Taiwan Museum, 47(1): 83–99. Serène R (1984) Crustacés Décapodes Brachyoures de l’Ocean Indien occidental et de la Mer Rouge. Xanthoidea: Xanthidae et Trapeziidae. Avec un Addendum par Crosnier, A. Carpiliidae et Menippidae. Faune tropicale, 24: 1–349, pls. 1–48. Stimpson W (1858) Prodromus descriptionis animalium evertebratorum, quae in Expeditione ad Oceanum Paciicum Septentrionalem, a Republica Federata missa, Cadwaladaro Ringgold et Johanne Rodgers Ducibus, observavit et descripsit. Pars IV. Crustacea Cancroidea et Corystoidea. Proceedings of the Academy of Natural Sciences of Philadelphia, 10: 31–40. Tan HH, Tan SK, Tan K, Lai JCY, Mendoza JC & Tan SH (2014) Christmas Island and Pulu Keeling Expeditions 2010 to 2012. Field work and locality records. Rafles Bulletin of Zoology, Supplement 30: this issue. Tweedie MWF (1950) The fauna of Cocos-Keeling Islands, Brachyura and Stomatopoda. Bulletin of the Rafles Museum, 22: 105–148, pls. 16–17. Ward M (1934) Notes on a collection of crabs from Christmas Island, Indian Ocean. Bulletin of the Raffles Museum, 9: 5–28, pls. 1–3. ACKNOWLEDGEMENTS The authors are grateful for the support from the Christmas Island National Park, the Pulu Keeling National Park, the Queensland Museum and the Rafles Museum of Biodiversity Research during the 2010–2012 expeditions to Christmas Island and the Cocos (Keeling) Islands. We also thank the expedition team members who were instrumental in collections and data gathering on-site: Tan Heok Hui, Tan Swee Hee, Joelle Lai, Tan Kai-xin, Tan Siong Kiat (NUS, Singapore); Peter Davie (Queensland Museum, Brisbane); Tohru Naruse, Yoshihisa Fujita (University of the Ryukyus, Okinawa), Shih Hsi-Te (National Chung Hsing University, Taiwan) and Max Orchard (CI National Park). We thank Tan Heok Hui and Tohru Naruse for providing some of the colour photographs used in this paper, Martyn Low for help with literature search, and Lee Bee Yan for assistance with some specimen measurements. Finally we thank Shane Ahyong, Paul Clark & Tohru Naruse for their valuable comments on the drafts of this paper. LITERATURE CITED Adams A & White A (1849) Crustacea. Part 2. In: Adams A (ed.) The Zoology of the Voyage of H.M.S. Samarang Under the Command of Captain Sir Edward Belcher, During the Years 1843–1846, Part 2. Benham & Reeve London, pp. i–viii, 33–67, pls. 7–13. Alcock A (1898) Materials for a carcinological fauna of India. No. 3. The Brachyura Cyclometopa. Part I. The family Xanthidae. Journal of the Asiatic Society of Bengal, Calcutta, (2)6(1): 67–233. Balss H (1938) Die Dekapoda Brachyura von Dr. Sixten Bocks Pazifik-Expedition, 1917–1918. Göteborges Kungliga Vetenskaps-och Vitterhets-Samhälles Handlingar, ser. B, 5(7): 1–85. Dana JD (1851) On the classiication of the Cancroidea. American Journal of Sciences and the Arts, (2)12(34): 121–131. Dana JD (1852a) Conspectus Crustaceorum, etc., Conspectus of the Crustacea of the exploring expedition under Capt. Wiles, U.S.N., including the Crustacea Cancroidea Corystoidea. Proceedings of the Academy of Natural Sciences of Philadelphia, 6: 73–86. Dana JD (1852b) Crustacea. Part I. United States Exploring Expedition. During the years 1838, 1839, 1840, 1841, 1842. Under the command of Charles Wilkes, U.S.N. Vol. 13. C. Sherman, Philadelphia, 685 pp. 304