Scientists have found new species of river dolphin in the Araguaia River Basin in Central Brazil for the first time since 1918, which they believe are highly endangered. River dolphins, Botos, are the most endangered dolphins in the world with 75% of its different species have been found threatened and are on the verge of extinction.

The research, which has been published in PLOS ONE, marks exciting news for biologists and conservationists.

Howard Rosenbaum, Director of the Wildlife Conservation Society's Ocean Giants program, in New York, claims the new discovery to be amazing because it will help in understanding as how these animals became distinct species. It will also help in understanding the cause of extinction of such species.

Researchers compared DNA samples of the Araguaian river dolphins with that of the other dolphin species and found it to be totally different. After analyzing the degree of difference, researchers revealed that the Araguaian river dolphins were separated from other dolphin species by about two million years ago.

Rosenbaum praised team of Brazil researchers for collecting robust data regarding the Araguaian river dolphins, showing genetic and physical differences between the Araguaian botos and other botos.

Some differences have been stated by the researchers between the two species. They said that the Araguaian botos have unique 'diagnostic characters' in maternally inherited DNA. Also, there are some differences based on compelling size in cranial features and number of teeth.

Rosenbaum added that there is need to look at additional specimens in order to name these new species. He said that an appeal to the Society for Marine Mammalogy asking for formal species designation will be the next step for naming of these new species.