58 Accepted by P. Castro: 9 Mar. 2011; published: 5 Apr. 2011 ZOOTAXA ISSN 1175-5326 (print edition) ISSN 1175-5334 (online edition) Copyright © 2011 · Magnolia Press Zootaxa 2809: 58–66 (2011) www.mapress.com/ zootaxa/ Article Leelumnus radium, a new genus and species of pilumnid crab from marine encrusting communities in Singapore (Crustacea: Decapoda: Brachyura: Pilumnidae) JOSE CHRISTOPHER E. MENDOZA 1 & PETER K. L. NG 1, 2, 3 1 Raffles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore, 6 Science Drive 2, S6-03-01, 117546 Singapore. E-mail: dbsjose@nus.edu.sg 2 Tropical Marine Science Institute, National University of Singapore, 18 Kent Ridge Road, S2S, 119227 Singapore. E-mail: peterng@nus.edu.sg 3 Corresponding author Abstract A new genus and new species of pilumnid crab is described from marine encrusting communities in Singapore. Leelumnus gen. nov. is morphologically similar to Latopilumnus Türkay & Schuhmacher, 1985, and Aniptumnus Ng, 2002, in the general shape of the carapace, chelipeds, ambulatory legs and morphology of the male thoracic sternum, but can be distinguished by the morphologies of the front and anterolateral margin of the carapace, as well as the unique structure of the male first gonopod. Only the type species, L. radium sp. nov. is currently assigned to the new genus. Keywords: Pilumnoidea, new genus, new species, taxonomy, Singapore Introduction During an ongoing study on the diversity of marine encrusting communities in Singapore by the Tropical Marine Science Institute, National University of Singapore, several species of brachyurans were collected from buoys, channel markers and other floating and semi-submerged structures. Among these were several specimens of an unusual pilumnid crab which superficially resembled species of Latopilumnus Türkay & Schuhmacher, 1985, and Aniptumnus Ng, 2002, but differed in a number of key features. The purpose of the present study is to describe these specimens as a new genus and new species of Pilumnidae. The following abbreviations are used: G1 = male first gonopod; G2 = male second gonopod; P3 = third pereo- pod (second ambulatory leg); P5 = fifth pereopod (fourth ambulatory leg). Measurements recorded (in millimeters) are of the carapace width and length, respectively. The specimens examined are deposited in the Nationaal Natuurhistorisch Museum (The Naturalis), Leiden (RMNH); The Natural History Museum, London (NHM); and the Zoological Reference Collection, Raffles Museum of Biodiversity Research, National University of Singapore (ZRC). The classification used follows that of Ng et al. (2008). Taxonomic account Family Pilumnidae Samouelle, 1819 Subfamily Pilumninae Samouelle, 1819