The Raffles Bulletin of Zoology (2002)


The taxonomy of the finless porpoise (Neophocaena phocaenoides), while better-studied than that of many species of small cetaceans, still suffers from some uncertainties and a general lack of data from most of the range. In this study, skull morphometric and meristic data were collected from 218 specimens from throughout the range of the species. Bivariate and multivariate Principal Components Analyses (PCA) were used to examine the sample for geographic variation. Results indicated that there is a great deal of geographic variation in the size and shape of skulls of porpoises from different areas. The two primary types of finless porpoise found in tropical and temperate waters showed some separation in both the PCA and rostrum shape analyses (but with some overlap in all features analyzed). However, there was not strong support from skull morphology for their distinctness at the species level. The temperate form, asiaeorientalis-type, is found in coastal and riverine waters of Japan, Korea, and northern China. It is relatively large (total length up to 227 cm and adult CBL 209-251 mm), with a narrow dorsal ridge (<1.3 cm), a relatively narrow rostrum, and adult coloration ranging from black to light gray. The tropical form, phocaenoides-type, occurs in the Indian Ocean (including the Persian Gulf) and South China Sea. Some populations of the latter are small (perhaps not exceeding 160 cm total length), and adult CBL ranges from 181-245 mm. It has a wide dorsal ridge (>3.4 cm), relatively wide rostrum, and dark-gray adult coloration. Two geographic populations were recognized within the asiaeorientalis-type, and three within the phocaenoides-type. Further work, especially analyses of skulls from unstudied portions of the range, systematic studies on dorsal ridge width, and molecular genetics, are needed to clarify taxonomic relationships and to identify stocks for management.