Decapoda, Brachyura) and a Key to Such Larvae from the Brazilian Coast

Home , Geograpsus, Geograpsus lividus, Grapsus grapsus

THE FIRST ZOEAL STAGE OF TWO SPECIES OF GRAPSIDAE (DECAPODA, BRACHYURA) AND A KEY TO SUCH LARVAE FROM THE BRAZILIAN COAST

A. FRANSOZO1), J. A. CUESTA2) and M. L. NEGREIROS-FRANSOZO1) 1) NEBECC (Group of Studies on Crustacean Biology, Ecology and Culture), Departamento de Zoologia, Instituto de Biociências, Centro de Aqüicultura, Universidade Estadual Paulista, C. P. 510, Cep 18618-000 Botucatu, São Paulo, Brazil 2) Departamento de Ecologia, Facultad de Biologia, Universidad de Sevilla, Apdo. 1095, E-41080 Sevilla, Spain

ABSTRACT

First zoeal stages of the grapsinid Goniopsis cruentata (Latreille, 1803) and the sesarminid Aratus pisonii (H. Milne Edwards, 1837), are described and illustrated. Grapsinae zoeae can be distinguished from the other grapsid larvae by the absence of lateral spines on the carapace and the reduction of the antennal exopod to a small seta. A key to the first zoeal stage of the Brazilian coast Grapsidae is provided.

RÉSUMÉ

Les premiers stades zoé du grapsinide Goniopsis cruentata (Latreille, 1803) et du sesarminide Aratus pisonii (H. Milne Edwards, 1837) sont décrits et figurés. Les zoés de Grapsinae peuvent être distinguées de celles des autres larves de Grapsidae par l'absence d'épines latérales sur la carapace et la réduction de l'écaille exopodiale de l'antenne à une petite soie. Une clef du premier stade zoé des Grapsidae de la côte brésilienne est fournie.

INTRODUCTION

Decapod classification is based on adult characters which are influenced by adaptations to different life styles. There are many taxonomic uncertainties re- sulting from the difficulty of recognizing apomorphic features in adult crustaceans. However, according to Rice (1980), the adaptations of adult brachyurans are not reflected in larval development. Most marine decapods have comparable planktonic larvae, and giving more consideration to larval characters would hopefully solve many of the problems of existing classifications. 332

The known Brazilian fauna is composed of 302 brachyuran species (Melo, 1996), of which only 25% have their complete larval development described. Among the Brachyura, there are 22 species of littoral Grapsidae, distributed in four subfamilies. The species with reference to larval descriptions, are the following: Grapsinae: Pachygrapsus gracilis (Saussure, 1858) studied by Ingle (1987) and Brossi-Garcia & Rodrigues (1993), Pachygrapsus transversus (Gibbes, 1850) by Ingle (1987) and Cuesta & Rodriguez (1994), Planes cyaneus Dana, 1852 by Konishi & Minigawa (1990), and Geograpsus lividus (H. Milne Edwards, 1837) by Cuesta (unpubl. data). Sesarminae: Chasmagnathus granulatus Dana, 1851 studied by Boschi et al. ( 1967), Aratus pisonii (H. Milne Edwards, 1837) by Warner (1968), Cyclograp- sus integer (H. Milne Edwards, 1837) by Gore & Scotto (1982), Metasesarma rubripes (Rathbun, 1897) by Diaz & Ewald (1968) and Montu et al. (1990), Sesarma ricordi H. Milne Edwards, 1853 by Díaz & Ewald (1968), Sesarma rectum Randall, 1840 by Fransozo & Hebling (1986), and Armases angustipes (Dana, 1852) by Kowalczuk (1994); the larvae described by Aikawa (1937) as Grapsus grapsus (Linnaeus, 1758) should probably be ascribed to a species of this subfamily (Cuesta et al., in press). Varuninae: Cyrtograpsus altimanus Rathbun, 1914 studied by Scelzo & Bas- tida (1979), Euchirograpsus americanus A. Milne Edwards, 1880 by Wilson (1980), and Cyrtograpsus angulatus Dana, 1851 by Boschi ( 1981 ). Plagusiinae: Plagusia depressa (Fabricius, 1775) studied by Wilson & Gore (1980), and Percnon gibbesi (H. Milne Edwards, 1853) by Paula & Hartnoll (1989). At present there are no larval data of Pachygrapsus corrugatus (Von Martens, 1872), Armases benedicti (Rathbun, 1897), Sesarma crassipes Cano, 1889, Cyr- tograpsus affinis (Dana, 1851), and Euchirograpsus kingsleyi (Miers, 1885). Abele (1992) reviewed all the known American species of Sesarma and some species were moved to the new genus Armases. For instance, Sesarma angustipes changed to Armases angustipes, and Sesarma ricordi to Armases ricordi. Later, Niem (1993) also referred Metasesarma rubripes to the genus Armases. Only more descriptions of reared larvae will lead to identifications of planktonic zoeae and a more valid classification of decapod crustaceans. This paper aims to facilitate the identification of planktonic grapsid larvae from the Brazilian coast by providing the first description of zoea I of Goniopsis cruentata and a redescription of the same stage of Aratus pisonii, both hatched in the laboratory.