Differences in the external morphology of two sympatric species of bottlenose dolphins (Genus tursiops) in the waters of China

Clear genetic and osteological characters exist to distinguish 2 sympatric species of bottlenose dolphins (genus Tursiops) in the waters of China, How ever, these characters are not useful for the identification of free-rangin g dolphins, To determine if these species could be differentiated by extern al morphology, a discriminant analysis was performed on 8 external morphome tric characters of 57 specimens, 40 of which were classified a priori as T, truncatus and 17 as T. aduncus using genetic, osteological, and other info rmation. External morphological separation of the 2 species was highly sign ificant. Furthermore, discriminant scores were nonoverlapping, and classifi cation functions were successful in classifying several new specimens from the waters of China and Indonesia. Rostrum length as an absolute measure an d as a proportion of total body length or snout-to-eye length revealed nono verlapping distributions for the 2 species in the waters of China and thus offered useful field characters for classifying fresh carcasses, stranded i ndividuals, captive specimens, photographs, and in some cases free-ranging individuals.