Estudo taxonômico das espécies de Scyliorhinus do grupo haeckelii/besnardi (Carcharhiniformes, Scyliorhinidae) das regiões Sudeste e Sul do Brasil (Oceano Atlântico Sul Ocidental

Abstract

The family Scyliorhinidae forms the largest group of sharks with at least 16 genera and 160 species. Known as catsharks, their representatives are characterized by having a slender body shorter than the caudal region, with the first dorsal fin over or behind the pelvic fin, characteristically elongated eyes and triangular pectoral fins, parallel to the body. Belonging to this family, the genus Scyliorhinus includes 16 species presenting a varied and widely used coloration patterns in taxonomic studies. Such patterns have generated problems as species identification, especially for the two species recognized for the Western South Atlantic, Scyliorhinus haeckelii and S. besnardi, considered here as belonging to the haeckelii/besnardi group. This study reviewed to revise the taxonomy of the genus Scyliorhinus haeckelii/besnardi group through a comparative study of external and skeletal anatomy, including morphometric and meristic features in order to clarify the morphological distinction of species, suggesting possible synonyms and describing new species. The specimens analyzed were obtained off Rio de Janeiro to Rio Grande do Sul states, all deposited in the ichthyological collection of the Universidade do Estado do Rio de Janeiro (UERJ). The laboratory work included literature review, identifying the color patterns, preservation, biometrics, statistical analyzes, anatomical preparation, description and production of diagrams and photographs, addressing the most relevant structures. The results obtained allowed the description of the general pattern of the genus Scyliorhinus of the Western South Atlantic, on the basis of the external morphology, coloration, dermal denticles, skulls, jaws, teeth, gill arches, fins and claspers. Specimens classified in the 'haeckelii' and 'besnardi' color pattern had no morphological and statistics differences. In this study, it were also found two other different patterns besides the haeckelii/ besnardi pattern, here called "negrinho" and "intermediate", considered new species and described here as Scyliorhinus sp. 1 and S. sp. 2. According to these results, the species S. besnardi is here considered a synonym of S. haeckelii, as the latter was the first to be described. An identification key to the species of Scyliorhinus of the Western South Atlantic is provided in the present study. It is concluded that more detailed anatomical and taxonomic studies on the other species of the genus Scyliorhinus are needed to better understand the relationships among its members and expansion of knowledge about the biology of these sharks