Araguaia dolphin
| Araguaia dolphin | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Skull and mandible of the holotype . |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Inia araguaiaensis | ||||||||||||
| Hrbek , Farias , Dutra & Da Silva in Hrbek, Da Silva, Dutra, Gravena , Martin & Farias, 2014 |
The Araguaia dolphin ( Inia araguaiaensis ) is a species of river dolphin found in northeastern Brazil that was only newly described in January 2014 . It is the first newly described river dolphin since 1918, the year the description of the Chinese river dolphin ( Lipotes vexillifer ), which was probably extinct between 2004 and 2006, was made . The previously known distribution area of the Araguaia dolphin includes the upper and middle Rio Araguaia and some tributaries coming from the Brazilian state of Goiás . The species may also be found in the Rio Tocantins and possibly in the entire river basin of Rio Araguaia and Rio Tocantins above the Tucuruí reservoir .
features
Compared to its closest relatives, the Amazon dolphin ( Inia geoffrensis ) and the Bolivian dolphin ( Inia boliviensis ), the Araguaia dolphin has a wider skull (measured at the parietal bone ), a wider upper jaw and fewer teeth per half of the lower jaw (24–28; 25–29 for I. geoffrensis and 31–35 for I. boliviensis ). The front 19 to 21 pairs of teeth in both jaws are conical , the rear 6 to 8 (molars) have a pointed apex that extends from the crown to the lip side and a recess on the tongue side.
Systematics
The Araguaia dolphin is the sister species of the Amazon river dolphin ( Inia geoffrensis ) and has by this during the Gelasian about 2 million years ago separated , as the basin of the Rio Araguaia and Tocantins from the Amazon basin was cut off. The sister group of the clade from Inia araguaiaensis and Inia geoffrensis is Inia boliviensis . I. boliviensis was isolated about 2.9 million years ago by the Teotonio rapids in the upper Rio Madeira area.
literature
- Hrbek, Tomas; Da Silva, Vera Maria Ferreira; Dutra, Nicole; Gravena, Waleska; Martin, Anthony R .; Farias, Izeni Pires. 2014. A New Species of River Dolphin from Brazil or: How Little Do We Know Our Biodiversity. In Turvey, Samuel T. PLoS ONE 9: e83623. doi: 10.1371 / journal.pone.0083623