Range extensions along western Atlantic for Epialtidae crabs ( Brachyura , Majoidea ) genera Acanthonyx Latreille , 1828 and

The present study provided information extending the known geographical distribution of three species of majoid crabs, the epialtids Acanthonyx dissimulatus Coelho, 1993, Epialtus bituberculatus H. Milne Edwards, 1834, and E. brasiliensis Dana, 1852. Specimens of both genera from different carcinological collections were studied by comparing morphological characters. We provide new data that extends the geographical distributions of E. bituberculatus to the coast of the states of Paraná and Santa Catarina (Brazil), and offer new records from Belize and Costa Rica. Epialtus brasiliensis is recorded for the first time in the state of Rio Grande do Sul (Brazil), and A. dissimulatus is reported from Quintana Roo, Mexico. The distribution of A. dissimulatus, previously known as endemic to Brazil, has a gap between the states of Espírito Santo and Rio de Janeiro. However, this restricted southern distribution is herein amplified by the Mexican specimens.

Acanthonyx dissimulatus Coelho, 1993 is a small crab known to occur from Piauí to Bahia (Coelho and Torres, 1993;Melo, 1996;Coelho et al., 2008) and São Paulo State (Mantelatto and Corrêa, 1996).It lives in shallow waters until depths of 25m, and can be found on hard substrates, sandy bottoms or mostly associated to aquatic vegetation the geographical distributions of three species of epialtid crabs: Acanthonyx dissimulatus is reported from Mexico; Epialtus bituberculatus to the coast of the states of Paraná and Santa Catarina (Brazil), and offer new records from Belize and Costa Rica; and E. brasiliensis is recorded for the first time in the state of Rio Grande do Sul (Brazil).

Material and Methods
As part of a research project on the systematic of decapod crustaceans, specimens of both genera collected by us and from different carcinological collections were studied by comparing morphological characters based on Rathbun (1925Rathbun ( , 1933)), Coelho and Torres (1993), Melo (1996) and Hendrickx (1999).
The examined material was deposited in the Crustacean Collection of the Department of Biology (CCDB), Faculty of Philosophy, Sciences and Letters of Ribeirão Preto (FFCLRP), University of São Paulo (USP).Complementary specimens for analysis were obtained by loans from the following crustacean collections: Universidade Federal de Pernambuco (DOUFPE), Museu Nacional do Rio de Janeiro (MNRJ), Universidade Federal do Rio Grande do Sul (UFRGS), University of Louisiana-Lafayette, Zoological Collections (ULLZ), Universidad Nacional Autónoma de México (UNAM), and Museum of Zoology of Universidad de Costa Rica (UCR).We measured the carapace length (CL) with a vernier caliper (0.01 mm) in all specimens analyzed, from the posterior to the anterior margin, including the rostrum.

Remarks: The distribution of A. dissimulatus, previously known as endemic to
Brazil (Coelho and Torres, 1993), has a gap between the states of Espírito Santo and Rio de Janeiro.However, this restricted southern distribution is herein amplified by the Mexican specimens (CCDB 2430).Furthermore, A. dissimulatus is very similar to A. petiverii H.
Milne Edwards, 1834 (Coelho and Torres, 1993), another species that also occurs in Brazil and Mexico (Retamal, 1981;Hiyodo et al., 1994;Hendrickx, 1999;Marcano and Bolaños, 2001;Emparanza et al., 2007;present study).Acanthonyx dissimulatus has not been cited from Mexico possibly because of misidentification for A. petiverii.In larger males of A. dissimulatus, the propodus of chelipeds with fingers considerably gaping when closed, and fixed finger and dactylus are smooth.In A. petiverii, fingers are denticulate, and the propodus of chelipeds with fingers slightly gaping when closed both in male and female (Garth, 1958;Coelho and Torres 1993;pers. obs.).Such characters are used to differentiate between the two species, although there is a lot of variation relying on the size and sex (pers.obs.).In addition, molecular analysis using different genes is under way to confirm and refine this aspect.
Both species of Epialtus from Brazil have similar habitat, coexisting on the same algae (Mantelatto and Corrêa, 1996;Melo, 1996;Mantelatto et al., 2004;pers. obs.), suggesting similar habits and structures.Carapace and rostrum morphology are also very similar (Rathbun, 1925;Melo, 1996), and the presence of a proximal spine on the propodus ventral surface in the last three ambulatory pereopods is the most important feature that identifies E. brasiliensis (with spine) and E. bituberculatus (spine absence).
Remarks: The material identified as E. brasiliensis (ULLZ 12624; ULLZ 6695; CCDB 1887) was examined and identified correctly as E. bituberculatus.Therefore, the extension of the geographic distribution range was possible due to these analyzes, because of the additional material (UCR 1038; UFRGS 580), and analyzes of our own specimens (CCDB 2430).Epialtus brasiliensis has been cited from Salvador (Gouvêa, 1986), but in northeast of Brazil this species is only known in Ceará (Fausto-Filho, 1970;Coelho et al., 2008).Thus, Almeida and Coelho (2008) considered the records from Bahia doubtful; it may be the result of insufficient sampling (Lima Júnior et al., 2010) or even mistaken for other species.

Final Comments
Following the carcinological tendency in recent years -due the increase of new projects, new collections and new groups of carcinologists -range extensions of decapod crustaceans have been recorded in many regions worldwide (Rahayu and Ng, 2000;Tavares and Amouroux, 2003), including the Brazilian coast (e.g.Mantelatto andDias 1999, Mantelatto et al., 2001;Cobo et al., 2002;Alves et al., 2006;Camargo et al., 2010;Almeida et al., in press).Range extensions of the epialtid crabs A. dissimulatus, E. bituberculatus and E. brasiliensis were relevant mainly for biogeographic and taxonomic studies.do Semi-Árido, Mossoró) and Racuel Collins (Smithsonian Tropical Research Institute, Panama) for their help and for the facilities during the collections, for making available some essential fresh specimens, and for lending the material from the collections used in our research.Additional support to this project was provided by the Fundação de Amparo à Pesquisa do Estado de São Paulo -FAPESP (Biota 2010/50188-8; Coleções Científicas 2009/54931-0) and to FLM by CNPq (Research Grants 472746/2004-9, 491490/2004-6, 473050/2007-2, and 471011/2011-8;Research Scholarships PQ 301261/2004-0 and302748/2010-5).The partial support and assistance of the Postgraduate Program in Comparative Biology of FFCLRP/USP; STRI for enabling FLM to travel to Panamá during the development of the course on Crustacean biology and taxonomy; members of the LBSC, during fieldwork; Ivana Miranda, Alexandre Almeida and anonymous reviewers for the revision of the text and suggestions and Julia Hetem for English revision, are gratefully acknowledged.