A New Species of River Dolphin from Brazil or: How Little Do We Know Our Biodiversity

Abstract

True river dolphins are some of the rarest and most endangered of all vertebrates. They comprise relict evolutionary lineages of high taxonomic distinctness and conservation value, but are afforded little protection. We report the discovery of a new species of a river dolphin from the Araguaia River basin of Brazil, the first such discovery in nearly 100 years. The species is diagnosable by a series of molecular and morphological characters and diverged from its Amazonian sister taxon 2.08 million years ago. The estimated time of divergence corresponds to the separation of the Araguaia-Tocantins basin from the Amazon basin. This discovery highlights the immensity of the deficit in our knowledge of Neotropical biodiversity, as well as vulnerability of biodiversity to anthropogenic actions in an increasingly threatened landscape. We anticipate that this study will provide an impetus for the taxonomic and conservation reanalysis of other taxa shared between the Araguaia and Amazon aquatic ecosystems, as well as stimulate historical biogeographical analyses of the two basins.

Testing the Effects of Barriers on the Genetic Connectivity inPodocnemis erythrocephala(Red-Headed Amazon River Turtle): Implications for Management and Conservation

“…In addition to structuring populations of P. erythrocephala and P. expansa, rapids and waterfalls in the Amazon basin also structure fish species Ochoa et al 2015), crocodilians , and dolphins (Gravena et al , 2015Hrbek et al 2014). Rapids also structure entire fish communities (Torrente-Vilara et al 2011).…”

Projections of hydrology in the Tocantins-Araguaia Basin, Brazil: uncertainty assessment using the CMIP5 ensemble

“…The rivers contain about 300 species of fish, most of which are migratory, including long-whiskered M a n u s c r i p t catfish (Hypophthalmus marginatus) and flannel mouth characiforms (Prochilodus nigricans) (Ribeiro et al 1995). Freshwater dolphins, including the recently discovered Inia araguaiaensis, are also known to reside in the river (Hrbek et al 2014).…”

A 17-My-old whale constrains onset of uplift and climate change in east Africa

“…In comparison, South American Sotalia fluvatilis, a river dolphin, has a normal range that reaches an elevation of ∼100 m, where river depths are 10-30 m, 3,600 km up the Amazon drainage from the Atlantic Ocean (Table 1) (15). In each of these cases, the riverine distribution of modern cetaceans is facilitated by sufficient water discharge in low-gradient rivers and the absence of shallow bedrock rapids and waterfalls (15,16).…”