Morfologia do aparato hióide de algumas espécies de odontocetos do sul do Brasil

Abstract

Morphology of the hyoid apparatus of some species of odontocetes from southern Brazil. The hyoid apparatus of odontocetes serves as a major attachment point for the muscles and ligaments that subserve breathing, sound production and swallowing. However, most of the literature on anatomy does not consider the bones of this region, presenting general osteological descriptions without considering the comparative aspects. This study sought to determine the intra and interspecific variations of the ossified hyoid apparatus elements from six species of odontocetus. We studied 96 hyoid apparatuses from the following species: Phocoena spinipinnis (n = 1), Pontoporia blainvillei (n = 20), Sotalia guianensis (n = 37), Stenella frontalis (n = 13), Steno bredanensis (n = 6) and Tursiops truncatus (n = 19). Among the six species analyzed, P. spinipinnis, P. blainvillei and S. guianenses presented a diagnostic feature of this apparatus, while the others were best described morphometrically when considering all the hyoid apparatus bones. Intraspecific variation was registered with greater amplitude in T. truncatus, while S. guianensis showed sexual dimorphism. The morphology of the hyoid apparatus proved to be important in the differentiation and characterization of all studied species.