The taxonomic status of common dolphins Delphinus spp. in South African waters

  • T Samaai Department of Zoology, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa; current address: CSIR Environmentek, Coastal Programme, PO Box 17001, Congella 4001, South Africa
  • PB Best Mammal Research Institute, University of Pretoria, Pretoria 0002, South Africa
  • MJ Gibbons Department of Zoology, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
Keywords: common dolphin, <i>Delphinus capensis</i>, <i>Delphinus delphis</i>, South Africa, taxonomy

Abstract

Aside from gender differences, a principal components analysis of skull measurements of 72 adult common dolphins from South Africa failed to distinguish more than one form of Delphinus. Plots of rostral length against zygomatic width indicated most could be referred to the long-beaked form D. capensis, but three individuals lay outside this range, two of which were within the range for the short-beaked form D. delphis from the North Pacific. These were smaller individuals with significantly shorter beaks, longer flippers and wider flukes, and the colour patterns of two agreed completely or mostly with criteria for delphis. Their tooth counts were within (but close to the upper end of) the range for D. delphis, whereas other common dolphins in the region were within the range for D. capensis. Vertebral counts for all Delphinus from South Africa were similar and were well below those for D. capensis from the North Pacific. It is concluded that a smaller form of Delphinus, with characteristics mostly resembling those of D. delphis, occurs in South African waters, but (because of small sample size and the lack of complete agreement with published criteria for D. delphis from the North Pacific) its exact taxonomic relationship to D. capensis in this region is unclear.

Keywords: common dolphin; Delphinus capensis; Delphinus delphis; South Africa; taxonomy

African Journal of Marine Science 2005, 27(2): 449–458
Published
2005-11-04
Section
Articles

Journal Identifiers


eISSN: 1814-2338
print ISSN: 1814-232X