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The horned curassow or southern helmeted curassow (''Pauxi unicornis'') is a species of bird in the Cracidae family. It is found in Bolivia. Its natural habitats are subtropical or tropical moist lowland forests and subtropical or tropical moist montane forests. It is threatened by habitat loss. Until 2004 the horned curassow was classified as Vulnerable by the IUCN Red List due to a small and declining population, but was changed to Endangered in 2005 due to an estimated smaller range and greater rinsk from human activities.〔 In Bolivia the potential habitat of subspecies ''P. unicornis unicornis'' may cover an area of 4,000 km2 including the national parks: Amboró, Carrasco and Isiboro Sécure. Despite concentrated fieldwork there are many parts of this potential habitat in which no individuals have found, for example the most north west 2,000 km2.〔 ==Taxonomy and systematics== In 1937 while in Bolivia Mr M. A. Carriker found two birds, a male and female, which were in the cracid family. The specimens were subsequently described as a new species by James Bond and Rodolphe Meyer de Schauensee in 1939 and given the scientific name ''Pauxi unicornis'' placing it in a genus ''Pauxi'' alongside the species ''P. pauxi''.〔 In 1969 another two birds, again a male and female were discovered which resembled those found by Mr. Carriker in 1937. However this time they were found in Peru a long way from the previous ''P. unicornis'' discoveries in Bolivia. These Peruvian specimens were described by John Weske and John Terborgh in 1971 as a new subspecies of ''P. unicornis'' which they named in honour of Maria Koepcke.〔 Although the consensus at the time of discovery for ''P. unicornis'' to be a species with two subspecies in the genus ''Pauxi'', many different suggestions have been made since. Some suggestions relate to the grouping of species and subspecies within the genus ''Pauxi''. In 1943 Wetmore and Phelps described a new subspecies of the closely related ''P. pauxi'' called ''P. p. gilliardi''. When Wetmore and Phelps looked at the three ''Pauxi'' forms known at the time, they concluded that ''P. p. gilliardi'' was an intermediate form between ''P. pauxi'' and ''P. unicornis''. As a result of this they grouped all three forms into a single species with ''unicornis'' becoming a subspecies of ''pauxi''.〔〔 This position was subsequently rejected by Charles Vaurie who argued that ''P. pauxi'' and ''P. unicornis'' were not conspecific. When Weske and Terborgh discovered the subspecies ''koepckeae'' they concluded ''pauxi'' and ''unicornis'' should be considered separate species.〔〔 Additional studies confirmed ''koepckeae'' to be distinct.〔 Consensus for the common name is Sira curassow. Other taxonomic suggestions discuss whether the genus ''Pauxi'' should stand alone or be grouped with other genera. In 1965 François Vuilleumier suggested the ''Pauxi'' species should be moved into a single genus alongside all the other species in the closely related genera ''Mitu'', ''Crax'' and ''Nothocrax''. Just two years later Charles Vaurie opposed this 'lumping' of species and argued that ''Pauxi'', ''Mitu'', ''Crax'' and ''Nothocrax'' should each be their own genera.〔 Not content with either of these two options Delacour and Amadon suggested that ''Pauxi'' and ''Mitu'' should indeed be grouped with ''Crax'', but that ''Nothocrax'' was distinct enough to be its on genus. Many subsequent authors followed Vaurie, Delacour and Amadon in having ''Nothocrax'' as a sister clade to ''Pauxi'', ''Mitu'' and ''Crax'', while most have followed Vaurie in having the three other clades as three distinct genera.〔〔〔 Recent mitochondrial analysis suggests that ''P. unicornis'' is a sister species to ''Mitu tuberosum'', while the other ''Pauxi'' species, ''P. pauxi'', is sister to the combined ''Mitu'' and ''P. unicornis'' clade. This means the genus ''Pauxi'' is not monophyletic but paraphyletic.〔Pereira 2004〕 The paraphyly of ''Pauxi'' could be due to incomplete lineage sorting, where a gene tree is inconsistent with its species tree, however it is less important for deep phyolenetic splits. Because of this, Pereira ''et al'' conclude incomplete lineage sorting is unlikely to account for the paraphylic ''Pauxi'' genera because, according to their own analysis, ''Mitu'' and ''Pauxi'' diverged approximately 6.5mya.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「horned curassow」の詳細全文を読む スポンサード リンク
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