![]() ![]() Inia geoffrensis boliviensis has populations in the upper reaches of the Madeira River, upstream of the rapids of Teotonio, in Bolivia. Inia geoffrensis geoffrensis inhabits most of the Amazon River, including rivers Tocantins, Araguaia, low Xingu and Tapajos, the Madeira to the rapids of Porto Velho, and rivers Purus, Yurua, Ica, Caqueta, Branco, and the Rio Negro through the channel of Casiquiare to San Fernando de Atabapo in the Orinoco river, including its tributary: the Guaviare. Subspecies The Bolivian river dolphin is a subspecies of Inia geoffrensis In addition, a 2014 study identifies a third species in the Araguaia-Tocantins basin, but this designation is not recognized by any international organization and the Committee on Taxonomy of the Society for Marine Mammalogy suggests this analysis is not persuasive. Therefore, the Bolivian river dolphin is currently recognized as a subspecies. ![]() As such the species level distinction once held is not supported by current results. A recent study, with more comprehensive sampling of the Madeira system, including above and below the Teotonio Rapids (which were thought to obstruct gene flow), found that the Inia above the rapids did not possess unique mtDNA. In 2002, following the analysis of mitochondrial DNA specimens from the Orinoco basin, the Putumayo River (tributary of the Amazon) and the Tijamuchy and Ipurupuru rivers, geneticists proposed that genus Inia be divided into at least two evolutionary lineages: one restricted to the river basins of Bolivia and the other widely distributed in the Orinoco and Amazon. boliviensis was a different species based on skull morphology. humboldtiana skulls were morphologically distinct and recommended that it be elevated to species status. humboldtiana is not distinguishable from I. Comparative morphological research also indicates that I. Molecular analysis suggests that the Orinoco dolphins are derived from the Amazon population and are not genetically distinct. humboldtiana (Orinoco river dolphin), was first described in 1977. geoffrensis (Amazon river dolphin) and I. The IUCN and Committee on Taxonomy of the Society for Marine Mammalogy recognize two subspecies: I. There is ongoing debate about the classification of species and subspecies. There is no consensus on when and how their ancestral species penetrated the Amazon basin they may have done so during the Miocene from the Pacific Ocean, before the formation of the Andes, or from the Atlantic Ocean. Today, however, the Amazon river dolphin has been reclassified into the superfamily Inioidea. Originally, the Amazon river dolphin belonged to the superfamily Platanistoidea, which constituted all river dolphins, making them a paraphyletic group. The species Inia geoffrensis was described by Henri Marie Ducrotay de Blainville in 1817. Taxonomy An Amazon river dolphin as depicted in Brehms Tierleben, 1860s It is difficult to train and a high mortality rate is seen among captive individuals. It is the only species of river dolphin kept in captivity, mainly in Venezuela and Europe. Threats include incidental catch in fishing lines, direct hunting for use as fish bait or predator control, damming, and pollution as with many species, habitat loss and continued human development is becoming a greater threat. In 2018, this species was ranked by the International Union for Conservation of Nature (IUCN) as endangered, with a declining population. They also consume other animals such as river turtles, aquatic frogs, and freshwater crabs. They have one of the widest ranging diets among toothed whales, and feed on up to 53 different species of fish, such as croakers, catfish, tetras and piranhas. The fin size, unfused vertebrae, and its relative size allow for improved manoeuvrability when navigating flooded forests and capturing prey. The dorsal fin, although short in height, is regarded as long, and the pectoral fins are also large. Like other toothed whales, they have a melon, an organ that is used for bio sonar. Sexual dimorphism is very evident, with males measuring 16% longer and weighing 55% more than females. Adults acquire a pink color, more prominent in males, giving it its nickname "pink river dolphin". The Amazon river dolphin is the largest species of river dolphin, with adult males reaching 185 kilograms (408 lb) in weight, and 2.5 metres (8.2 ft) in length. The three subspecies are distributed in the Amazon basin, the upper Madeira River in Bolivia, and the Orinoco basin, respectively. araguaiaensis) within the clade is still unclear. humboldtiana (Orinoco river dolphin) while position of Araguaian river dolphin ( I. boliviensis ( Bolivian river dolphin) and I. Three subspecies are currently recognized: I. The Amazon river dolphin ( Inia geoffrensis), also known as the boto, bufeo or pink river dolphin, is a species of toothed whale endemic to South America and is classified in the family Iniidae. ![]()
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