Bull. nur. Hist. Mus. Land. (Zool.) 68( 1 ): 13-18 yy (-3>szt^- \j Issued 27 June 2002 A new species of freshwater crab (Brachyura, Potamoidea, Potamonautidae) from Principe, Gulf of Guinea, Central Africa NEIL CUMBERLIDGE Department of Biology, Northern Michigan University. Marquette. Michigan 49855, U.S.A. PAUL F. CLARK Department of Zoology, The Natural History Museum. Cromwell Road, London, SW7 5BD, U.K. JONATHAN BAILLIE Institute of Zoology, Zoological Society of London, Regents Park, London NW1 4RY, UK. CONTENTS Introduction 13 Systematic Account 13 P. principe sp. nov 13 Ecological Notes 17 Acknowledgements 17 References 17 Synopsis. A new species of freshwater crab of the genus Potamonautes Macleay. 1 838 is described from Principe ( Democratic Republic of Sao Tome and Principe), an island in the Gulf of Guinea oft the coast of Central Africa. The specimens were collected during a recent zoological expedition by the Zoological Society of London. This is also the first record of a freshwater crab on the island of Principe. INTRODUCTION The freshwater crabs reported on here were collected during a zoological expedition to the island of Principe, made recently by the Zoological Society of London. The island of Principe, together with the island of Sao Tome, constitutes a small independent country (The Democratic Republic of SaoTome and Principe) in the Gulf of Guinea. Principeis thesecondinachainof volcanic islands that make up the Atlantic Ocean Islands group, that lies off the coasts of Cameroon, Equatorial Guinea and Gabon. The other islands in this group are Bioko, Sao Tome and Annobon. Bioko is closest to the mainland and has two species of potamonautid freshwater crabs, Sudanonautes floweri (De Man, 1901) and S. granulatus (Balss, 1929), both of which are also found in nearby Cameroon (Cumberlidge, 1993, 1995, 1999). SaoTome is the third island in the group, and has one endemic species of freshwater crab, Potamonautes margaritarius (A. Milne-Edwards, 1886). There are no records of freshwater crabs occurring on Annobon, the fourth island in the chain, and the furthest from the mainland. Until the present report, freshwater crabs were not known to be present on Principe. The new species from Principe was collected from streams and nearby land in cloud forest in the remote roadless highland region in the southwest part of the island. The new species is compared to Potamonautes anchietae (De Brito-Capello, 1871) and to P. margaritarius, but differs from each in a number of important characters (Bott, 1953, 1955, 1964). Although the speci- mens from Principe are both subadult females, and ideally an adult male is needed to make a definitive identification, a description is nevertheless provided here, based on several unique somatic characters of the specimen. Characters of the gonopods, male abdo- men, and male chelipeds will be described when more material (including an adult male) becomes available. Figures were prepared using a camera lucida, and the specimens weredepositedinTheNaturalHistoryMuseum,London,U.K. (BMNH). Abbreviations: cw, distance across the carapace at the widest point; cl, carapace length measured along the median line, from the anterior to the posterior margin; ch, carapace height, the maximum height of the cephalothorax); fw, front width measured along the anterior margin; s, thoracic stemite; e, thoracic episternite; s4/s5, s4/s5, s5/s6. s6/s7, s7/s8, sternal sulci between adjacent thoracic sternites; s4/e4, s5/e5, s6/e6, s7/e7, episternal sulci between adjacent thoracic sternites and epistemites; P1-P5, pereiopods 1-5, al-a6, abdominal segments 1-6, a7, telson of the abdomen. SYSTEMATIC ACCOUNT Family POTAMONAUTIDAE Bott, 1970 Genus POTAMONAUTES MzcLeay, 1838 Potamonautes principe sp. nov. (Fig. 1) Material examined Holotype. BMNH 2001.6907. 1 subadult female, cw 40.5, cl 27.5, ) The Natural History Museum. 2002