Variações cranianas em Tursiops truncatus (Mammalia: Certartiodactyla) em diferentes localidades dos oceanos, com ênfase na costa sul-americana: uma abordagem pela técnica de morfometria geométrica

Abstract

Delphinids are the most ecologically diverse cetaceans, occurring in a wide range of latitudes in pelagic and coastal waters, including estuarine and freshwater regions. The taxonomy is especially confusing on genus Tursiops, since most forms has been synonymized in the specie Tursiopstruncatus. However, recent studies suggest that Tursiops is polyphyletic. The bottlenose dolphinT.truncatus habit coastal and pelagic waters in all tropical and temperate regions.Tursiopstruncatus is considered polymorphic and this characteristic makes the target of bitter taxonomic discussions about what are regional variations or different taxonomic entities. The objective was to analyze the cranial morphological variability of T. truncatus in different ocean regions to provide arguments for taxonomic discussions involving this genus. Two dimensional Geometric Morphometric analysiswas performed in skulls on dorsal and lateral views of specimens occurring in the Pacific North East, North West Atlantic, South West Atlantic, East North Atlantic, East South Atlantic and Indian oceans. There were significant differences between all groups, including differences between specimens recognizedasT. gephyreus and T. truncatus in the Atlantic coast of South America. The skull variationsare related to the type of environment in which different groups occur and may be relating to the foraging, prey capture and echolocation system. In addition, variations along the Atlantic coast of South America can be explained by the possible recognition of two species in this region