A suspected new river dolphin species has emerged in Brazil, and scientists warn that it is highly endangered.

River dolphins (also known as botos) are among the rarest, and most endangered, dolphins in the world. Three of the four known species are listed as “threatened” by the International Union for Conservation of Nature (IUCN). The discovery of a wholly new species—the first such find in a century—is thus exciting news for biologists and conservation officials.

Scientists led by Tomas Hrbek of theUniversidade Federal do Amazonas in Manaus, Brazil, announced the existence of the proposed new species of river dolphin in PLOS ONE on January 22. Discovered in the Araguaia River Basin in central Brazil, the animals were isolated from other botos (Inia geoffrensis and Inia boliviensis) in the adjacent Amazon Basin to the west by a series of rapids and a small canal…