Composition and seasonal variations of the brachyuran crabs (Crustacea, Decapoda) living on Sargassum cymosum in the Ubatuba region, São Paulo, Brazil

Luis Medina Mantelatto, FernandoKácia Corrêa, Eunice

The aim of this study was to characterize the brachyuran crabs living onSargassum cymosum C. AGARDH, 1820, with emphasis on seasonal variation of specimens collected on three different beaches inthe Ubatuba region (23Q 26" Sand 45Q 02" W). The algae were collected manually by snorkellingduring lowtide infourdifferentseasons, from January to December 1995, bagged and stored frozen.ln the laboratory, the samples were thawed at room temperature, transferred to a basin containing water and then carefully shaken branch by branch. The animais were sorted out under a camera lucida, counted and preserved in 70% alcohol. A total of 382 specimens were collected, belonging to three families, with seven genera and ten species. Epialtus brasillensis DANA, 1852was the most abundant and Constant species in ali areas, followed by Hexapanopeus schmitti RATHBUN, 1930 and Microphrys bicornutus(LATREILLE, 1825). Theoccurrence ofAcantonyx dissimulatus COELHO, 1991-1992 in São Paulo State is documented at first time. Species frequency varied over the year at the sites sampled.ln general, ItaguáBeach presented a larger number of species. The highest and lowest densities occurred in the winter and summer, respectively. key words: Brachyura, composition, crabs, phytal, Sargassum.