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Scientists in Brazil have discovered a new species of river dolphin, the first new species to be found since 1918.
Known as Inia araguaiaensis, it can mostly be found in a 932-mile stretch of the Araguaia-Tocantins River system in Brazil, according to a report published in PLOS One Journal.
Scientists estimate anywhere between 600 to 1,500 of these dolphins currently live in the basin and they propose they be known as “Araguaian boto" dolphins.
River dolphins are some of the rarest and most endangered animals in the world — of the four known species, three are on the International Union for Conservation of Nature's 'Red List'.
Most river dolphins live throughout the Amazon River Basin, but this new species is concentrated in the Araguaia-Tocantins River system, almost completely disconnected from the Amazon basin thanks to a series of waterfalls, rapids and other geological barriers.
The scientists behind the report believed there was a chance dolphin sightings in the Araguaia-Tocantins were a new species because it's so isolated from the Amazon.
The new Araguaia river dolphin has less teeth than other species of river dolphins and is smaller.
But the real differences were found in the DNA samples, which helped the scientific team to conclude the dolphin was a new species.
"In science you can never be sure about anything," said Dr Tomas Hrbek of the Federal University of Amazonas to the BBC. "We looked at the mitochondrial DNA, which is essentially looking at the lineages, and there is no sharing of lineages."
The researchers said they are worried about the Araguaian boto dolphins' survival because there appears to be low genetic diversity and the ever growing threat of human development in the region.