Cephalorhynchus is a genus in the dolphin family Delphinidae.
It consists of four species:
| Image | Scientific name | Common name | Distribution |
|---|---|---|---|
| Commerson's dolphin | C. commersonii | Argentina including Puerto Deseado, in the Strait of Magellan and around Tierra del Fuego, and near the Falkland Islands, near the Kerguelen Islands in the southern part of the Indian Ocean | |
| Chilean dolphin | C. eutropia | coast of Chile | |
| Heaviside's dolphin | C. heavisidii | coast of northern Namibia at 17°S and as far south as the southern tip of South Africa | |
| Hector's dolphin | C. hectori | coastal regions of New Zealand | |
The species have similar physical features—they are small, generally playful, blunt-nosed dolphins—but they are found in distinct geographical locations.
A phylogenetic analysis in 2006 indicated the two species traditionally assigned to the genus Lagenorhynchus, the hourglass dolphin L. cruciger and Peale's dolphin L. australis are actually phylogenetically nested among the species of Cephalorhynchus, and they suggest these two species should be transferred to the genus Cephalorhynchus. Some acoustic and morphological data support this arrangement, at least with respect to Peale's dolphin.[1]
According to a study in 1971, Peale's dolphin and the Cephalorhynchus species are the only dolphins that do not whistle (no acoustic data are available for the hourglass dolphin). Peale's dolphin also shares with several Cephalorhynchus species the possession of a distinct white "armpit" marking behind the pectoral fin.[2]