A carcinofauna dos ambientes marinhos e costeiros das regiões sudeste e sul da Bahia, Brasil, ainda é pobremente conhecida. O objetivo deste estudo foi realizar um inventário da fauna de crustáceos decápodos do município de Ilhéus, localizado no sudeste da Bahia (14º47'55"S, 39º02'01"W). As amostragens foram realizadas de Fevereiro de 2001 a Fevereiro de 2005, nas zonas supra, meso e infralitoral. Os exemplares coletados foram fixados em etanol 70% e depositados na coleção de crustáceos da Universidade Estadual de Santa Cruz, Ilhéus (MZUESC). Foi coletado um total de 51 espécies pertencentes a 14 famílias. A família mais representativa em termos de número de espécies foi Ocypodidae, representada nas amostragens por 8 espécies. A distribuição geográfica conhecida para as espécies Alpheus heterochaelis (Caridea: Alpheidae), Merguia rhizophorae (Caridea: Hippolytidae) e Sesarma curacaoense (Brachyura: Sesarmidae) foi estendida. A ocorrência do siri exótico Charybdis hellerii, originário do Indo-Pacífico, foi registrada para o estuário do rio Cachoeira. Estes resultados indicam que os estuários de Ilhéus abrigam elevada riqueza de espécies.

The carcinofauna from marine and coastal environments from the southeast and southern Bahia, Brazil, is so far poorly known. The objective of this study was to survey decapod crustaceans occurring along the estuarine environments of Ilhéus, located on the southeast coast of Bahia (14º47'55"S, 39º02'01"W). Samplings were carried out from February 2001 to February 2005, covering supratidal, intertidal and subtidal habitats. Voucher specimens were fixed in ethanol 70% and deposited in the collection of Crustacea of the Universidade Estadual de Santa Cruz, Ilhéus (MZUESC). We report a total of 51 species, belonging to 14 families. The most representative family concerning the number of species was Ocypodidae, represented in our samples by 8 species. Geographic range known for the species Alpheus heterochaelis (Caridea: Alpheidae), Merguia rhizophorae (Caridea: Hippolytidae) and Sesarma curacaoense (Brachyura: Sesarmidae) was enlarged. The Indo-Pacific portunid crab Charybdis hellerii was recorded for the Cachoeira river estuary. The results indicate a high species richness of decapod crustaceans in the estuarine environments of Ilhéus.

The absence of morphological external characteristics that allow the recognition of the sex as well as the presence of both male and female gonopores in the same animal [except in some sexual forms of Parastacus nicoleti (Philippi, 1882)] gives rise to the hypothetical existence of some form of hermaphroditism in crayfishes belonging to the genus Parastacus Huxley, 1879. Specimens of Parastacus brasiliensis (von Martens, 1869) were collected in a rivulet at Mariana Pimentel municipality, Rio Grande do Sul, Brazil. In the laboratory they were reared and dissected. The results suggest that P. brasiliensis may be a sequential hermaphroditic species, but male and female gonadal tissues were not simultaneously present in the analized samples. In testes and ovaries two pairs of genital ducts are present; that connect, respectively, to the gonopores on the coxae of the fifth and the third pairs of pereiopods. In the females only the apertures and anterior ducts seem to be functional, while in the males only the apertures and posterior ducts may be functional. The existence of different degrees of obstruction in the female genital apertures and different degrees of projection in the male genital apertures was observed. The aspect of the gonopores were used to recognize, externally, the sex of animais.