Diferenças morfométricas de duas espécies do gênero Rhizoprionodon (Chondrichthyes, Carcharhinidae)

Abstract

Belonging to Carcharhinidae family, Rhizoprionodon porosus and R. terraenovae are may be confused as to the specific status, and most often has only the geographical criteria is used for discriminating to the species level as R. porosus is distributed only on the east coast of the American continent and R. terraenovae occurs in the west coast of the Atlantic in the Northern Hemisphere. The analysis of morphometric characters of the two species R. porosus and R. terraenovae, was conducted to ascertain differences in body shape, since genetic differences found using molecular markers of mitochondrial DNA may already have been morphologically expressed. To this end, measures 59 that are homologous parts of the body of 150 male and female newborns, and juveniles and adults were analyzed. Of these, 106 were R. porosus 44 were R. terraenovae collected in Brazil (off Pernambuco and Rio Grande do Norte states) or came from the collections of six different Museums; (MN / UFRJ), (MZUSP), (MOVI) (MNHN), (FMNH) and (FMNH). Univariate analyses indicated significant differences in measurements between species, which were observed in the multivariate analyses, depicted in projections of the first principal component ending up in a discriminant model made up of 4 measures, which classified species correctly with an mean accuracy of 81%. Therefore, the morphometric analyses confirm that the two species are distinct taxons delimited between the Gulf of Mexico and the northern Caribbean, suggesting an allopatric distribution.