Orcaella
| Snubfin dolphins | |
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| Orcaella brevirostris | |
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| Genus: | Orcaella Gray, 1866
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| Distribution of genus Orcaella | |
The snubfin dolphins (Orcaella) are a genus of dolphins containing two members: the Irrawaddy Dolphin and Australian Snubfin Dolphin. The genus was long believed to be monotypic with the only species being the Irrawaddy Dolphin; however, in 2005, genetic analysis showed that the Australian Snubfin Dolphin is closely related. Recent molecular analyses indicate that the genus Orcaella is closely related to the Orca of the genus Orcinus, the two of them together forming the subfamily Orcininae.
Taxonomy
Until 2005, Orcaella brevirostris was the only recognized species in the genus Orcaella. However, comparisons within the populations of Orcaella inhabiting the Asia region and populations inhabiting the Australia/New Guinea region show distinctions in habitat, morphology, and genetics [1]. Morphological differences include height of dorsal fin, skull shape, presence or absence of a median dorsal groove in front of the dorsal fin, and coloration. Genetic analysis constitutes a 5.9% difference between the two populations. [2] In 2005, these significant distinctions considered by Beasley, Arnold and Robertson warranted a taxonomic split of Orcaella into two separate species, Orcaella brevirostris and Orcaella heinsohni . Orcaella brevirostris known as the Irrawaddy Dolphin consists of the Asian population. The newly recognized species, Orcaella heinsohni known as the Australian Snubfin Dolphin, consists of the Australian/New Guinea population [3].
References
- ^ Ross, G. J. (2006). Review of the conservation status of Australia's smaller whales and dolphins. Department of the Environment and Water Resources.
- ^ Beasley, I., Robertson, K. M. and Arnold, P.. 2006. DESCRIPTION OF A NEW DOLPHIN, THE AUSTRALIAN SNUBFIN DOLPHIN ORCAELLA HEINSOHNI SP. N. (CETACEA, DELPHINIDAE). Marine Mammal Science 21: 365 -400
- ^ Beasley, Isabel L. (2007) Conservation of the Irrawaddy dolphin, Orcaella brevirostris (Owen in Gray, 1866) in the Mekong River: biological and social considerations influencing management. PhD thesis, James Cook University.
- LeDuc, R.G., Perrin, W.F., Dizon, A.E. (1999). Phylogenetic relationships among the delphinid cetaceans based on full cytochrome b sequences. Marine Mammal Science 15, 619–648.
- May-Collado, L., Agnarsson, I. (2006). Cytochrome b and Bayesian inference of whale phylogeny. Molecular Phylogenetics and Evolution 38, 344-354.