River dolphins worldwide are rare and endangered, but a new species has been added to their number for the first time in almost a century. Scientists in Brazil, writing in the journal PLOS One, say the Araguaia dolphin, named after the river where it was found, is a distinct species that formed around 2 million years ago when rapids cut it off from the rest of the Amazon river basin, reports the BBC.
It is very similar to the Amazon river dolphin, but DNA samples proved it was a different species, slightly smaller and with fewer teeth. It becomes the fifth known river dolphin species in the world (though one is thought to be extinct); the last was identified in 1918.
"It was something that was very unexpected, it is an area where people see them all the time, they are a large mammal, the thing is nobody really looked," the lead researcher says.
"It is very exciting." But he warns that there are only around 1,000 of the creatures in existence and its "future is pretty bleak," New Scientist reports.
Dams have fragmented its habitat, which has already been degraded by farming and ranching operations, and fishermen have been know to kill it as a pest.
(A new seafaring dolphin species was also recently discovered.)More From Newser