MAJOID CRABS FROM THE MOZAMBIQUE CHANNEL WITH THE DESCRIPTION OF A NEW SPECIES OF OXYPLEURODON MIERS, 1886 (DECAPODA, BRACHYURA)

BY

BERTRAND RICHER DE FORGES1) Kiwa Consulting, 5, rue Félix Franchette, 98800 Nouméa, New Caledonia

ABSTRACT

The study of the crabs collected in the Mozambique Channel in the Indian Ocean by the cruises MAINBAZA and MIRIKY permit the description of the new species Oxypleurodon holthuisi. The four single rostrum species from the Indian Ocean for which the genus Nasutocarcinus Tavares, 1991 was created are placed in Oxypleurodon.

RÉSUMÉ

L’étude des crabes du Canal de Mozambique récoltés lors des campagnes MAINBAZA et MIRIKY conduit à la description de l’espèce Oxypleurodon holthuisi. Les quatre espèces à rostre simple de l’Océan Indien pour lesquelles avaient été créés le genre Nasutocarcinus Tavares, 1991 sont placées dans le genre Oxypleurodon.

INTRODUCTION

During the last few decades, many deep-sea cruises in the Pacific Ocean have considerably increased our knowledge of crab taxonomy and their biogeography. In the epialtid genus Oxypleurodon Miers, 1886, there are now 23 species, all living in the upper bathyal zone of the Pacific (Richer de Forges & Ng, 2009a, b). The only species of this genus presently known in the Indian Ocean are O. luzonicum (Rathbun, 1916) and O. wilsoni Richer de Forges & Poore, 2008, from the west coast of Australia. In the rest of the Indian Ocean, another small group of crabs, very similar in shape, have

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© Koninklijke Brill NV, Leiden, 2010 Studies on Malacostraca: 645-653 646 CRM 014 – Fransen et al. (eds.), LIPKE BIJDELEY HOLTHUIS MEMORIAL VOLUME been placed in the genus Nasutocarcinus Tavares, 1991. The main difference between these two genera according to Tavares (1991) is that the rostrum is clearly bifid throughout its length in Oxypleurodon but only bifid at the tip in Nasutocarcinus. In 2009, during the deep-sea cruises in the Mozambique Channel, MAIN- BAZA along the coast of Mozambique and MIRIKY along the northwest coast of Madagascar, several specimens of epialtid crabs were collected. This new material contains two species. One, from Madagascar, is identified as Na- sutocarcinus difficilis (Guinot & Richer de Forges, 1985). Some specimens showing a very short bifid rostrum, are described here as a new species, Oxy- pleurodon holthuisi sp. nov. A re-examination of the material from the Indian Ocean, however, leads to the conclusion that Nasutocarcinus Tavares, 1991, is a junior subjective synonym of Oxypleurodon Miers, 1886. Material examined is deposited in the Muséum national d’Histoire naturelle, Paris (MNHN); and Zoological Reference Collection of the Raffles Museum of Biodiversity Research, National University of Singapore (ZRC). Measure- ments, in millimeters, are of the maximum postrostral carapace length fol- lowed by maximum carapace width.

TAXONOMIC ACCOUNT

Superfamily MAJOIDEA Samouelle, 1819

Family EPIALTIDAE MacLeay, 1838

Subfamily PISINAE, Dana, 1851 Genus Oxypleurodon Miers, 1886 Oxypleurodon Miers, 1886: 38; Tavares, 1991: 159 (in part); Webber & Richer de Forges, 1995: 510; Ng et al., 2008: 104; Richer de Forges & Poore, 2008: 63; Richer de Forges & Ng, 2009a: 250; 2009b: 2. Sphenocarcinus A. Milne-Edwards, 1875: pl. 17, fig 5; 1878: 135; Alcock, 1895: 193; Sakai, 1938: 277; 1976: 193; Griffin, 1976: 211; Takeda, 1980: 72; Guinot & Richer de Forges, 1985: 50; 1986a: 134; 1986b: 27; Tavares, 1991: 159 (in part); Richer de Forges, 1992: 3; 1995: 44; Richer de Forges & Ng, 2009b: 248. Rochinia A. Milne-Edwards, 1875: 86; Griffin & Tranter, 1986: 175 (in part); Tavares, 1991: 161 (in part). Nasutocarcinus Tavares, 1991: 169 (in part); Richer de Forges & Ng, 2009b: 250; Ng et al., 2008: 104. Remarks. — The history of the genus Oxypleurodon Miers, 1886, has been reviewed at length by Richer de Forges & Ng (2009a). The type species is O.