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Dolphin Species Discovered In The Amazon River

  |   Wildlife & Flora

Araguaian boto (Inia araguaiaensis)

Araguaian boto (Inia araguaiaensis)

A new species of river dolphin has been found in the Amazon river, the first of its kind for a century. The new species is named Araguaian boto (Inia araguaiaensis), or after the Araguaia River Basin that it calls home.

The discovery came when scientist Tomas Hrbek of the Federal University of Amazonas in Manaus, Brazil, and colleagues noticed that a group of river dolphins in the Araguaia was isolated from other Amazon dolphins by a series of rapids.

River Dolphin Skeleton

River Dolphin Skeleton

Taking DNA from these river dolphins they found that they significantly differed genetically from all other species in Brazil. TheInia araguaiaensis is smaller in size than the others, yet it has a wider skull. They were also found to have only 24 teeth per jaw, rather than the 25 to 29 found in the Amazon's other river dolphins.

The scientists estimate that the dolphin species diverged some two million years ago, corresponding to the separation of the Araguaia-Tocantins basin from the Amazon basin. They observed around 120 individuals over the course of a 12-week study, and estimate that there could be as few as 600 left across the whole river basin.

Amazon Map

Amazon Map

Given their low numbers and the large amount of hydroelectric dam construction in the area, conservation efforts are now underway, especially considering what happened to its Chinese cousin, the baiji which was discovered in 1918 but was declared extinct in 2006.

So the world now has five species of river dolphin (Bolivian, Amazon, La Plata, South Asian,  and now Araguaian), when we thought there were only four. Who knows: as scientists collect more genetic data, it may only be a matter of time before multiple species are discovered living in other isolated basins in the Amazon.


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