The objective of the present study is to characterize the physical and chemical environmental parameters of Ubatuba Bay (SP), as a subsidy for studies of the composition and distribution of benthic crustaceans which live on the non-consolidated sublittoral bottom of this area. Depth, temperature, salinity, dissolved oxygen, organic content and granulometric composition of the sediments were measured monthly from September/95 to August/96 in eight subareas of the bay. The bay presents an average depth of 9.3 m and is characterized by the following annual mean values for the hydrologic factors: temperature 23.8 o C, salinity 33.2‰ and dissolved oxygen 5.11 mg/l. The annual mean for the organic matter content of the bay bottom sediments was 11.8% and most subareas presented a grain size composition dominated by pelitic sediments. These peculiar abiotic characteristics are very important for the reproduction and development principally of brachyuran and anomuran crabs, and shrimps which have a close relationship with those substrates.Key words: Crustacea, environmental factors, sediment, organic content, Ubatuba, Brazil. RESUMO Caracterização dos parâmetros físicos e químicos da Enseada de Ubatuba, litoral norte de São Paulo, BrasilO presente trabalho objetivou a caracterização de alguns parâmetros físicos e químicos da Enseada de Ubatuba (SP), como subsídio para estudos sobre composição e distribuição de invertebrados bentônicos associados ao substrato não-consolidado desta área, além de servir para comparações com cenários futuros da região. Foram estabelecidas oito subáreas para a amostragem dos parâmetros ambientais (profundidade, temperatura, salinidade e teor de oxigênio dissolvido na água, teor de matéria orgânica e granulometria do sedimento de fundo). Em todas a subáreas as coletas foram efetuadas mensalmente, durante três dias consecutivos, de setembro de 1995 a agosto de 1996. As amostras de água foram coletadas com uma Garrafa de Nansen e o sedimento de fundo com um pegador do tipo Van Veen (1/40 m 2 ). Os valores médios dos parâmetros encontrados na Enseada foram: profundidade (9,3 ± 3,66 m), temperatura (23,8 ± 0,62 o C), teor de oxigênio dissolvido (5,11 ± 0,29 mg/l), salinidade (33,2 ± 0,35‰) e teor de matéria orgânica (11,8 ± 5,35%). Quanto à granulometria, houve predomínio das areia fina e muito fina. Entre as subáreas, pode-se constatar diferenças significativas na profundidade, no teor de oxigênio dissolvido, no teor de matéria orgânica e na granulometria do sedimento. Os valores encontrados permite-nos caracterizá-la como uma enseada com um padrão semelhante às adjacentes, mas com parâmetros hidrológicos e sedimentológicos fortemente estabe-

The freshwater prawn Macrobrachium amazonicum is widely distributed in South America, and occupies habitats with a wide range of salinities. Several investigations have revealed the existence of wide intraspecific variability among different populations, although the understanding of this variability is still fragmentary and incomplete. We compared and characterized inland and coastal populations of M. amazonicum from Brazil, using molecular data (16S and COI mtDNA) to describe the degree of variability, structure, and relationships among them. Genetic divergence rates among populations showed variability at the intraspecific level. All the analyses evidenced significant genetic divergence among populations, structuring them in three groups: I- inland waters of the Amazonian Hydrographic Region (HR); II- Paraná/Paraguay HR; and III- coastal systems of northern and northeastern Brazil. Phylogenetic reconstructions revealed that the populations form a single monophyletic clade, which supports their characterization as a single species. Clade I was a sister clade of that formed by clades II and III, which were themselves sister clades. Populations from Sertãozinho/ Miguelópolis and Avaré, introduced into the state of São Paulo, may have originated from natural populations in the states of Mato Grosso do Sul and Pará, respectively. Geographical isolation probably contributed to the observed variation, and if this isolation continues, M. amazonicum may undergo speciation within its broad geographical distribution. The sequences obtained here can be used as name-tags for population identification, and the DNA barcodes are useful to identify the origin of specimens used in different freshwater-prawn cultures or introduced populations of unknown origin.

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SUMMARY: The objective of this study was to characterize the pattern of shell utilization by Paguristes tortugae, from infralittoral areas of Anchieta Island (Ubatuba, São Paulo State, Brazil) using the percentage of the different shell types occupied and the morphometric relationship between hermit crabs and occupied shells. Specimens were collected monthly (January to December 1998) by SCUBA diving. The animals and the shells were measured and weighed. A total of 2,429 hermit crabs were captured occupying 21 species of gastropod shells. The shells more occupied were Pisania auritula (35.49%), Cerithium atratum (27.83%), Morula nodulosa (12.70%) and Leucozonia nassa (6.83%), respectively. There was differential shell occupation between sexes: males and ovigerous females occupied in higher percentage P. auritula shells while the non-ovigerous females occupied C. atratum. Regression analysis showed best correlation between the size of the crabs (shield length) and shell dry weight. This study showed that shell occupation by P. tortugae involves inter-and intraspecific competition as well as shell type availability in the field.Key words: Anomura, Crustacea, population, shell resource. RESUMEN: PAUTAS DE UTILIZACIÓN DE CONCHAS POR EL CANGREJO ERMITAÑO PAGURISTES TORTUGAE (DIOGENIDAE)DELA ISLA DE ANCHIETA, BRASIL MERIDIONAL. -El objetivo del presente estudio consistió en caracterizar las pautas de utilización de conchas por Paguristes tortugae en áreas infralitorales de la isla de Anchieta (Ubatuba, Estado de Sao Paulo, Brasil) utilizando el porcentaje de los distintos tipos de concha ocupados y la relación morfométrica entre los ermitaños y las conchas ocupadas. Los especímenes fueron muestreados mensualmente (enero a diciembre 1998) mediante inmersión con bombonas de aire comprimido. Los animales y las conchas fueron medidos y pesados. Un total de 2429 cangrejos ermitaños fueron capturados y se registraron un total de 21 especies de conchas de gasterópodos utilizadas por los mismos. Las conchas más ocupadas fueron Pisania auritula (35.49%), Cerithium atratum (27.83%), Morula nodulosa (12.70%) y Leucozonia nassa (6.83%). Se detectó una ocupación diferencial de conchas respecto al sexo del ermitaño: machos y hembras ovígeras ocuparon conchas de P. auritula en una mayor proporción, mientras que las hembras no ovígeras ocuparon preferencialmente C. atratum. Un análisis de regresión mostró la mayor correlación entre la talla de los cangrejos (longitud del escudo cefalotorácico) y el peso seco de la concha. Este estudio mostró que la ocupación de conchas por P. tortugae comporta competencia inter-e intraespecífica, y depende también de la disponibilidad de conchas en el campo.

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The current taxonomy of two poorly known hermit crab species Pagurus forceps H. Milne Edwards, 1836 and Pagurus comptus White, 1847 from temperate Pacific and Atlantic coastlines of South America is based only on adult morphology. Past studies have questioned the separation of these two very similar species, which occur sympatrically. We included specimens morphologically assignable to P. forceps and P. comptus in a phylogenetic analysis, along with other selected anomuran decapods, based on 16S ribosomal gene sequences. Differences between samples putatively assigned to either P. forceps and P. comptus were moderate, with sequence similarity ranging from 98.2 to 99.4% for the fragments analyzed. Our comparison of mitochondrial DNA sequences (16S rRNA) revealed diagnostic differences between the two putative species, suggesting that P. forceps and P. comptus are indeed phylogenetically close but different species, with no genetic justification to support their synonymization. The polyphyly of Pagurus is not corroborated here among the represented Atlantic species, despite obviously complex relationships among the members of the genus.

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SUMMARY: Population structure and reproductive season of the portunid crab Callinectes ornatus were studied in animals collected from the Ubatuba bays, São Paulo, Brazil (23°20' to 23 o 35' S and 44 o 50'to 45 o 14' W). The samples were taken in three trawls performed every other month from January 1991 to May 1993. A total of 3,829 specimens of C. ornatus were obtained. Their size ranged from 9.3 to 84.6 mm (carapace width). Their median size based on their cephalothoracic width and their size frequency were determined as well. Their reproduction was continuous, with variable proportions of ovigerous females. The highest incidence of ovigerous females occurred in January 1991, 1992and 1993 and March and November 1992. The oscillations of the environmental factors between the seasons are not so intense in subtropical regions, therefore allowing the continuity of the physiological process of growth and reproduction throughout the year.