A new species of river dolphin has been described from the Araguaia river in Brazil. Inia araguaiaensis was previously believed to just be Boto, but the two species haven't interbred in two million years.
They are slightly smaller and have a different number of teeth, but otherwise look very similar, hence why they have go unnoticed for so long.
BBC News - Brazil dolphin is first new river species since 1918
They are slightly smaller and have a different number of teeth, but otherwise look very similar, hence why they have go unnoticed for so long.
BBC News - Brazil dolphin is first new river species since 1918