RESUMO
The definition and scope of the genus Carcharhinus has undergone several changes over the years and recent molecular studies have questioned its monophyly by the inclusion of other carcharhinid genera. Although many descriptions of chondrocranium are available for Carcharhinus species, some inconsistences and divergences are found in the literature, mainly regarding the foramina of the orbital region. In this study, the chondrocranium of the silky shark, Carcharhinus falciformis, from specimens caught at the Brazilian coast and the terminology of its components is revised has been described. Chondrocrania of other Carcharhinus species and carcharhinid genera are also examined in order to investigate the phylogenetic significance of chondrocranial morphology. Three new anatomical terms and nine chondrocrania characters are proposed and described in detail. The chondrocranial morphology varies widely among Carcharhinus species mainly regarding the rostrum and nasal capsules. The chondrocrania of Prionace, Nasolamia, and Negaprion are similar to Carcharhinus species and reveal the need to further explore the relationships among these genera. Characters potentially informative for systematics are the shape of rostral node, the preorbital process, and the subethmoidal fossa, and the occurrence of an epiphyseal notch and foramen, and must be included in phylogenetic studies encompassing other carcharhiniforms.
Assuntos
Tubarões , Animais , Brasil , Cartilagem , Filogenia , CrânioRESUMO
The distribution of elasmobranchs in the bottom gillnet fishery of 'Barra de Guaratiba' (RJ, Brazil) was checked between March 1982 to May 1985. An amount of 892 specimens of 25 species were registered. Rhizoprionodon porosus, R. lalandii and Sphyrna lewini were considered constants during the whole period. Rhizoprionodon species use the area as a nursery ground, meanwhile others (as Sphyrna lewini juveniles), for recruitment. None relationship between catches and moon phases were detected. Recent data, collected between 2004 and 2007, indicate the fishery pattern does not change, besides the gillnet length have grown and the catches fall.
A distribuição de elasmobrânquios na pesca de emalhe de fundo da Barra de Guaratiba (Município do Rio de Janeiro, Brasil) foi acompanhada periodicamente, entre março de 1982 e maio de 1985. Foram identificados 892 exemplares de 25 espécies. Rhizoprionodon porosus, R. lalandii e Sphyrna lewini mostraram-se constantes ao longo de todo o período. Foram observados diferentes usos da região pelas espécies que a utilizam como área de reprodução (R. lalandii e R. porosus), ou para recrutamento (Sphyrna lewini). As capturas não demonstraram relação com a fase lunar. Observações realizadas mais recentemente, com visitas aperiódicas, entre 2004 e 2007, indicaram que o padrão pesqueiro continua o mesmo, ainda que o tamanho dos petrechos tenha aumentado e o volume das capturas tenha caído.
RESUMO
The distribution of elasmobranchs in the bottom gillnet fishery of 'Barra de Guaratiba' (RJ, Brazil) was checked between March 1982 to May 1985. An amount of 892 specimens of 25 species were registered. Rhizoprionodon porosus, R. lalandii and Sphyrna lewini were considered constants during the whole period. Rhizoprionodon species use the area as a nursery ground, meanwhile others (as Sphyrna lewini juveniles), for recruitment. None relationship between catches and moon phases were detected. Recent data, collected between 2004 and 2007, indicate the fishery pattern does not change, besides the gillnet length have grown and the catches fall.
A distribuição de elasmobrânquios na pesca de emalhe de fundo da Barra de Guaratiba (Município do Rio de Janeiro, Brasil) foi acompanhada periodicamente, entre março de 1982 e maio de 1985. Foram identificados 892 exemplares de 25 espécies. Rhizoprionodon porosus, R. lalandii e Sphyrna lewini mostraram-se constantes ao longo de todo o período. Foram observados diferentes usos da região pelas espécies que a utilizam como área de reprodução (R. lalandii e R. porosus), ou para recrutamento (Sphyrna lewini). As capturas não demonstraram relação com a fase lunar. Observações realizadas mais recentemente, com visitas aperiódicas, entre 2004 e 2007, indicaram que o padrão pesqueiro continua o mesmo, ainda que o tamanho dos petrechos tenha aumentado e o volume das capturas tenha caído.
RESUMO
The secondary sexual dimorfism in the shark Scyliorhinus haeckelii Ribeiro, 1907 is herein presented and analysed based on the morphology og tyhe dentition, jaw and snout shape, dermal denticles and the colour of 21 specimens of the species