New Species of River Dolphin: Freshwater Species of the Week

The cranium and mandible of the proposed new dolphin species, Inia araguaiaensis. Photography by National Institute for Amazonian Research

Scientists in Brazil proposed a new species of river dolphin this week, the first such designation for the highly endangered group in a century.

The proposed new species of river dolphin, the Araguaian boto (Inia araguaiaensis), was found in the Araguaia River Basin in central Brazil. The marine mammals were found to be 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.freshwater species of the week

The scientists who made the discovery were led by Tomas Hrbek of the Universidade Federal do Amazonas in Manaus, Brazil, and the work was published in PLOS ONE on January 22.

River dolphins are extremely rare thanks to dams that disrupt their habitat, hunting, loss of prey, and entrapment in fishing gear. Three of the four known species are listed as “threatened” by the International Union for Conservation of Nature (IUCN).

The scientists in Brazil observed about 120 of the proposed new species over 12 weeks. They estimate there are about 600 of the animals left in the Araguaian River Basin, meaning it should receive protected status if it is formally ruled a new species by the Society for Marine Mammalogy (the Society will likely need to see some more research before making a decision).

The proposed new species differs from other botos genetically, suggesting that it has been separate for about 2 million years, the scientists wrote. The Araguian boto also has different cranial features, they say, although they were only able to examine a few specimens that were already dead.

Learn more about the proposed new species of river dolphin here.


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