Review of the taxonomic status of humpback dolphins, genus Sousa

The present paper reviews the external and skeletal morphology of Sousa, based primarily on the large samples of South African and Australian material now available, and some new data from populations in the Arabian Gulf and at Hong Kong. The emphasis has been placed on variation within and between the popUlations as indicators of genetic interchange between populations or the lack of such interchange. We propose that the small differences observed in these limited samples do not provide sufficient evidence to support the presence of more than one species, under the name Sousa chinensis (Osbeck, 1765). Although this single species could be subdivided into three or more subspecies, we believe that this would be premature on our present level of knowledge. In resolving this situation, further morphological studies on the West African and southern Chinese populations, presently underway, will be most helpfuL In particular, data on Sousa are needed urgently on a specimen-by-specimen basis, from the South-East Asian region, especially for the populations around the southern islands and Papua New Guinea, in order to resolve their taxonomic and conservation status, as there is every possibility that this region supports a unique taxon of Sousa in the southern region.