Records of the Western Australian Museum Supplement No. 59: 117-123 (2000). DECAPOD CRUSTACEA OF CHRISTMAS ISLAND Gary J. Morgan Western Australian Museum, Francis Street, Perth, Western Australia 6000, Australia A total of 204 decapod crustacean species is listed shallow subtidal habitats of Christmas Island. The in Table 10. The list includes species recorded by genus Clibanarius appears to be absent, contrasting the previous workers noted below. The species with a previous report (Gibson-Hill, 1947a) of names are those currently used in the scientific populations of three species of Clibanarius in Flying literature and not necessarily the names cited by Fish Cove, a site well sampled for the present historical workers. The historical collections have survey (station 1). The extent of live coral appears not been examined and hence the accuracy of early to have diminished since the early studies of identifications cannot be ascertained. Christmas Island, and this may have affected the In comparison with other invertebrate groups, the faunal composition of many areas. crustacean fauna of Christmas Island, especially the The hermit crab family Paguridae is usually order Decapoda, has been well documented. regarded as relatively poorly represented in tropical Species of Crustacea have been recorded by Pocock seas and far less diverse or abundant than the (1887), Andrews (1900), De Man (1905), Calman Diogenidae. While less speciose on Christmas (1909), Balss (1934), Ward (1934), Gordon (1935), Island, the Paguridae comprised numerous Gibson-Hill (1947a; b), Tweedie (1947), George individuals of several small, cryptic species, often (1978) and Hicks et al. (1984). Most workers have aggregating under loose coral debris. Recent studies concentrated on the true crabs (Brachyura), with by the author indicate that Christmas Island is not particular emphasis on the terrestrial species, unique in this condition but rather that small although Morgan (1992) describes the hermit crabs. pagurids have been poorly collected from tropical The present survey was orientated towards the areas in the past. The definite identification of marine crustacean fauna, particularly of subtidal several species will require further study and will depths accessible only by SCUBA and hence poorly be the subject of a future paper. Orthopagurus harmsi sampled by previous workers. The marine hermit is a small commensal of serpulid worm tubes in crabs (families Diogenidae and Paguridae) and coral heads and was originally described from xanthoid crabs (families Xanthidae, Trapeziidae, Christmas Island (Gordon, 1935). Pilumnidae, Menippidae) were preferentially Two species of rock lobster, Panulirus peniciIlatus collected as these are dominant components of the and P. versicolor were collected, both having crustacean faunas of tropical intertidal and subtidal widespread distributions across the Indo-West waters, especially when associated with rocky and Pacific. A third species, P. longipes, is recorded for coral reefs. Dominant groups are xanthoid (80 Christmas Island by Calman (1909) and George species or subspecies), grapsid (20 species), and (1968). majid crabs (17 species), and hermit crabs (31 In the Brachyura, the families Majidae (decorator species). Seventy-five species are new records for crabs), Grapsidae (rock crabs) and superfamily Christmas Island. Xanthoidea (black-clawed crabs) are dominant in The general composition of the decapod terms of species diversity. Of the majids, crustacean fauna of Christmas Island is essentially Tylocarcinus dumerilii and Schizophrys aspera that expected for a tropical, oceanic Indo-West appeared quite common. Diversity of xanthoids is Pacific island environment. The crustacean fauna very high, as in most tropical reef areas of the Indo­ reflects the dominance of coral and coral rubble Pacific. Dominant genera are Pilodius, Liomera, habitats with relatively small areas of sand Trapezia and Tetralia, the latter two comprising substrate and the complete absence of mud and fine obligate symbionts of corals. silts. Grapsid crabs are a very obvious component of Hermit crabs are the most diverse of the Christmas Island intertidal and supratidal habitats anomuran fauna. The genera Calcinus and Dardanus and are quite well documented (eg. Hicks et al., are dominant in the Diogenidae both in terms of 1984). The present survey confirmed the presence numbers of species and individuals. Both are of a second species of Grapsus, G. albolineatus, characteristic genera of coral reef areas. previously recorded (as G. strigosus) by Calman In particular C. gaimardii, C. guamensis, C. minutus, (1909). C. sp. novo 1 and D. lagopodes are very common in Two species of Ocypodidae were collected during 118 G.J. Morgan this study, Ocypode ceratophthalma and O. cordimana, De Man, J.G. (1905). On species of Crustacea of the both recorded from Christmas Island by several genera Ptychognathus Stimps. and Palaemon Fabr. from previous workers. An additional species, O. kuhlii, Christmas Island. Proceedings of the Zoological Society has been reported by Tweedie (1947) and Gibson­ ofLondon 1905: 537-550. Hill (1947a) but was not found in this survey, nor is George, RW. (1968). Tropical spiny lobsters Panulirus it recorded by Hicks et al. (1984). spp., of Western Australia (and the Indo-West Pacific). Journal ofthe Royal Society ofWestern Australia Although no intensive effort was made durip.g the 51: 33-38. present study to collect land crabs, a specimen of a George, RW. (1978). The land and freshwater crabs of previously unrecorded terrestrial gecarcinid Christmas Island. Australian National Parks and species, Epigrapsus politus, was collected from West Wildlife Service Unpublished report, 22 pp. White Beach, together with an additional specimen, Gibson-Hill, CA. (1947a). Christmas Island. The nature presented to the museum party, from Flying Fish of the coast. Bulletin ofthe Raffles Museum 18: 8-17. Cove. This species is a relatively small gecarcinid, Gibson-Hill, CA. (1947b). Christmas Island. Field notes somewhat resembling a juvenile Cardisoma hirtipes, on the terrestrial crabs. Bulletin of the Raffles Museum and was found amongst rocks of the supralittoral 18: 43-52. zone. Gordon, I. (1935). On two new species of Crustacea from Several decapod groups, notably the caridean Christmas Island. Annals and Magazine of Natural shrimps, are still poorly documented for History (10)16: 629-637. Christmas Island and require further specialist Hicks, J., Rumpff, H. and Yorkston, H. (1984). Christmas attention. The non-decapod crustacean fauna is Crabs. Christmas Island Natural History Association. almost unknown. Morgan, G.J. (1992). The hermit crabs (Crustacea: Decapoda: Coenobitidae, Diogenidae, Paguridae) of Christmas and Cocos (Keeling) Islands, Indian Ocean, REFERENCES with description of a new species of Paguristes. Raffles Andrews, CW. (1900). Land crustacea. In: A Monograph Bulletin ofZoology 40: 163-174. of Christmas Island (Indian Ocean). British Museum Pocock, RI. (1887). V. Crustacea. In: Giinther A. Report (Natural History), London. pa,ges 163-165. on a zoological collection by officers of HMS Flying Balss, von H. (1934). Die Krabben der Reise J.W. Harms' Fish at Christmas Island, Indian Ocean. Proceedings of nach der Christmas-Insel und dem Malaiischen the Zoological Society of London 1887: 520. Archipel. Zoologische Abhandlungen 106: 225-237. Tweedie, M.W.F. (1947). On the Brachyura of Christmas Calman, W.T. (1909). On decapod Crustacea from Island. Bulletin ofthe Raffles Museum 18: 27-42. Christmas Island, collected by Dr C W. Andrews, Ward, M. (1934). Notes on a collection of crabs from F.RS., F.Z.S. Proceedings of the Zoological Society of Christmas Island, Indian Ocean. Bulletin of the Raffles London 1909: 703-713. Museum 9: 5-28. Table 10 List of Decapod Crustacea Key to symbols * Not collected during this survey + New record for Christmas Island Numbers = sampling stations (see Table 4.) Station numbers PENAEOIDEA PENAEIDAE * Penaeus sp. STENOPODIDEA STENOPODIDAE Stenopus hispidus (Olivier, 1811) 1 CARIDEA PALAEMONIDAE PONTONIINAE * Coralliocaris graminea (Dana, 1852) * Coralliocaris superba (Dana, 1852) PALAEMONINAE Macrobrachium lar (Fabricius, 1798) Waterfall stream, Hewans Spring, * Palaemon carcinus Fabricius, 1798 Dales ALPHEIDAE * Alpheus aff. collumianus Stimpson, 1861 * Alpheus malleodigitus (Bate, 1888) Decapod Crustacea 119 Table 10 (cont.) Station numbers * Athanas djiboutensis Coutiere, 1897 * Athanas dorsalis (Stimpson, 1861) * Synalpheus biunguiculatus (Stimpson, 1861) GNATHOPHYLLIDAE + Hymenocera picta Dana, 1852 1 HlPPOLYTIDAE * Lysmata seticaudata (Risso, 1816) THALASSOCARlDIDAE * Thalassocaris lucida (Dana, 1852) PALINURA PALINURlDAE * Panulirus longipes (A. Milne Edwards, 1868) Panulints penicillatus (Olivier, 1791) 3 Panulirus versicolor (Latreille, 1804) 1,9 SCYLLARIDAE + Parribacus antarcticus (Lund, 1793) 1,2 * Thenus orientalis (Lund, 1793) ANOMURA DlOGENIDAE + Aniculus retipes Lewinsohn, 1982 3,11 + Aniculus ursus (Olivier, 1811) 1,3 Calcinus elegans (H. Milne Edwards, 1836) 1,2,3,4,5 + Calcinus gaimardii (H. Milne Edwards, 1848) 1,2,3,4,5,6,8,10,14,15 + Calcinus guamensis Wooster, 1984 1,3,5,6,8,11,14,15 Calcinus laevimanus (Randall, 1839) 3,4 + Calcinus latens (Randall, 1839) 1,2,10,15 + Calcinus minutus Buitendijk, 1937 1,2,3,5,8,9,11,14,15 + Calcinus seurati Forest, 1951 4 + Calcinus lineapropodus Morgan & Forest, 1991 1,2 * Clibanarius corallinus (H. Milne Edwards, 1848) * Clibanarius sp. 1 * Clibanarius