Saturday, 25 January 2014

New species of river dolphin

The Araguaian boto (C) Nicole Dutra
The boto, Inia geoffrensis, popularly known as the pink dolphin, is widely distributed in the rivers of the Amazon basin. It is also found in the Araguaia-Tocantins river basin. Since the two basins became disconnected at the Pliocene-Pleistocene boundary, Tomas Hrbek and colleagues (here) asked if this really was the same species. They analysed morphological and molecular data (including mitochondrial genes), concluded that the Araguaian boto was a distinct species and named it Inia araguaiaensis. In addition they proposed that the boto found in the Bolivian sub-basin be raised from subspecies to species status as Inia boliviensis.     

Distribution map of species and subspecies of Inia
From Hrbek et al. PLoS ONE 2014: 9: e83623
(c) Hrbek et al. (Creative Commons)
Some time ago Dr. Vera da Silva, a co-author of the new study, afforded me the opportunity to study placentation in the boto and also the tucuxi (Sotalia fluviatilis), another dolphin found in the Amazon (here).

Placenta of the boto
From da Silva et al. RBE 2007; 5: 26
For more about these creatures including their place in folklore I recommend Journey of the Pink Dolphins: An Amazon Quest by Sy Montgomery.

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