Osteological differences between two sympatric forms of bottlenose dolphins (genus Tursiops) in Chinese waters

Although there has been extensive research on bottlenose dolphins (genus Tu rsiops), much controversy over the classification within this genus still e xists. Even though many morphological variants occur, the prevailing view i s for a single species, Tursiops truncatus (Montagu, 1821). To evaluate thi s view, two sympatric forms of bottlenose dolphins inhabiting Chinese water s were examined using multivariate statistical analyses of osteological dat a for two meristic and 18 cranial morphometric characters from 71 specimens . Cluster and principal components analyses revealed clear osteological sep aration of the two forms. Furthermore, the distributions of the total numbe r of vertebrae and several proportions of cranial characters were non-overl apping between the two forms. These results provided strong evidence that t he two sympatric forms of Tursiops in Chinese waters are isolated reproduct ively and do not support the current view of a monotypic genus. Classificat ion functions of a discriminant analysis and a key of several characters we re developed to help researchers identify unassigned specimens. Provisional names (T. truncatus and T. aduncus) were suggested, but a formal taxonomic revision of this genus is still required. However, regardless of the nomen clature, immediate amendments to all present wildlife conservation legislat ion are strongly urged.