LARVAL MORPHOLOGY OF THE SESARMID , ARATUS PISONII (H. MILNE EDWARDS, 1837) (, BRACHYURA, GRAPSOIDEA) FROM LABORATORY-REARED MATERIAL

BY

JOSÉ A. CUESTA1,3), MARCELO U. GARCÍA-GUERRERO2,4,7), ANTONIO RODRÍGUEZ1,5) and MICHEL E. HENDRICKX2,6) 1) Instituto de Ciencias Marinas de Andalucía (CSIC), Avenida República Saharaui, 2, E-11510 Puerto Real, Cádiz, Spain 2) Unidad Académica Mazatlán, Instituto de Ciencias del Mar y Limnología, UNAM, P.O. Box 811, Mazatlán, Sinaloa, 82000 México

ABSTRACT Three ovigerous females of the crab, Aratus pisonii (H. Milne Edwards, 1837) () were captured from a coastal lagoon in Mazatlán, Mexico. Larvae were reared in the laboratory from hatching to the megalopa stage. The morphology of the four zoeal stages and the megalopa is described and illustrated. Morphological comparisons are made with previous descriptions of this from Jamaica and Brazil, and with all known descriptions for the larvae of Armases Abele, 1989, the closest similar . Several differences are observed with regard to earlier descriptions of Aratus pisonii, and additional characters, such as the previously undescribed cephalothoracic setation of the larval stages and the mouthparts of the megalopa, are described and illustrated.

RÉSUMÉ Trois femelles gravides du crabe Sesarmidae Aratus pisonii (H. Milne Edwards, 1837) (Sesarmi- dae) ont été capturées dans une lagune côtière à Mazatlán, Mexique. Les larves de cette espèce ont été cultivées au laboratoire, depuis leur éclosion jusqu’au stade Mégalope. La morphologie des quatre stades Zoés et de la Mégalope est décrite et illustrée. Une comparaison morphologique avec les descriptions antérieures de cette espèce, réalisées en Jamaique et au Brésil, est présentée, ainsi qu’une comparaison avec toutes les larves connues des espèces de Armases Abele, 1989, le genre le plus proche de Aratus. Plusieurs différences sont notées en comparaison avec les descriptions antérieures de Aratus pisonii. Des caractéristiques supplémentaires sont ajoutées, notamment la se- tation du céphalothorax et des appendices buccaux de la Mégalope, non décrits à ce jour.

3) e-mail: [email protected] 4) e-mail: [email protected] 5) e-mail: [email protected] 6) e-mail: [email protected] 7) Present adress: CIIDIR-IPN, P.O. Box 280, Guasave, Sinaloa 81000, Mexico; e-mail: mgarciagu@ ipn.mx © Koninklijke Brill NV, Leiden, 2006 Crustaceana 79 (2): 175-196 Also available online: www.brill.nl 176 JOSÉ A. CUESTA ET AL.

INTRODUCTION

The Sesarmidae Say, 1817 are represented in the by four genera, i.e., Aratus H. Milne Edwards, 1837, Armases Abele, 1992, Metopaulias Rathbun, 1896, and Sesarma Say, 1817, with a total of 34 species (see Schubart et al., 2000, 2002, for a recent discussion of grapsoid ). The -tree crab, Aratus pisonii (H. Milne Edwards, 1837) is an amphi-American species reported from the Bahamas and southern to São Paulo, Brazil, including most of the Caribbean Islands (West Atlantic), and from Magdalena Bay and the central Gulf of California, Mexico, to Capon, (East Pacific) (Conde & Diaz, 1989; Abele & Kim, 1989; Hendrickx, 1995). Originally described from the Antilles, it is the only species of its genus. Adult A. pisonii live among mangrove (Rhizophora, Avicennia and Laguncularia) branches, roots, and twigs, from the supralittoral zone to the canopy, and feed on mangrove leaves, although specimens occasionally occur alongshore, on rocks and piles, bushes and wharves (Rathbun, 1918; Diaz & Conde, 1988; Carmona-Suárez & Conde, 1996). When hatching, larvae of this arboreal crab are released in the estuaries and coastal lagoons where are found. Many aspects of the life history features of A. pisonii and of its ecology have been documented (see Conde & Díaz, 1989; Díaz & Conde, 1989; Conde et al., 1995; De Arruda Leme, 2002; Negreiros-Franzoso, 2002; Nicolau & Oshiro, 2002; Chiussi, 2003). Diet (Schwamborn et al., 2002), distribution (Sankarankutty et al., 1995) and salinity tolerance of larvae (Díaz & Bevilacqua, 1986, 1987), visual orientation of megalopae (Díaz et al., 1995), and embryonic development (García Guerrero & Hendrickx, 2004) are some of the specific aspects related to the early life of A. pisonii that have been studied. Larval descriptions of Aratus pisonii have been made by Hartnoll (1965) (prezoea and zoea I), Warner (1968) (four zoeae and megalopa), and Fransozo et al. (1998) (zoea I). All these descriptions are incomplete (to differing degrees) and those by Hartnoll (1965) and Warner (1968) do not fit the modern standard for larval descriptions (see Clark et al., 1998). Studies on the effect of different salinities on larval development of Aratus pisonii (cf. Díaz & Bevilacqua, 1986, 1987) indicate that this species may present three larval sequences, i.e., with four, three, or even two zoeal stages prior to the megalopa, but these different sequences appear to be independent of salinity and other laboratory conditions (diet, photoperiod, temperature, etc.). As the previously published descriptions of larval stages of A. pisonii are thus inadequate, a new, complete, and detailed description was needed in order to make a comprehensive morphological comparison with the rest of the sesarmid genera. In the present study, therefore, the larval development of Aratus pisonii from the Pacific coast of Mexico is described and illustrated. Also, differences with