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''Akodon spegazzinii'', also known as Spegazzini's akodont〔Musser and Carleton, 2005, p. 1099〕 or Spegazzini's grass mouse,〔 is a rodent in the genus ''Akodon'' found in northwestern Argentina. It occurs in grassland and forest at above sea level. After the species was first named in 1897, several other names were given to various populations now included in ''A. spegazzinii''. They are now all recognized as part of a single, widespread and variable species. ''Akodon spegazzinii'' is related to ''Akodon boliviensis'' and other members of the ''A. boliviensis'' species group. It reproduces year-round. Because it is widely distributed and common, ''Akodon spegazzinii'' is listed as "Least Concern" on the IUCN Red List. ''Akodon spegazzinii'' is medium in size for the ''A. boliviensis'' species group. The coloration of its upperparts varies considerably, from light to dark and from yellowish to reddish brown. The underparts are yellow-brown to gray. The eyes are surrounded by a ring of yellow fur. The skull contains an hourglass-shaped interorbital region (between the eyes) and various features of the skull distinguish the species from its close allies. Head and body length is and body mass is . ''A. spegazzinii'' has 40 chromosomes. ==Taxonomy== ''Akodon spegazzinii'' was first described in 1897 from Salta Province by Oldfield Thomas on the basis of a collection made in late 1896 or early 1897 by mycologist Carlos Luigi Spegazzini, after whom the species was named.〔Thomas, 1897, pp. 214, 216; Beolen et al., 2009, p. 387; Musser and Carleton, 2005, p. 1099〕 Four years later, Joel Asaph Allen named ''Akodon tucumanensis'' from Tucumán Province, comparing it to various species now synonymized under ''Abrothrix olivaceus''.〔Allen, 1901, pp. 410–411; Musser and Carleton, 2005, p. 1090〕 Thomas named an additional species, ''Akodon alterus'', from La Rioja Province in 1919, and considered it closely related to ''A. spegazzinii''.〔Thomas, 1919, pp. 496–497〕 A fourth species, ''Akodon leucolimnaeus'', was described by Ángel Cabrera from Catamarca Province in 1926, but after 1932 it was associated with ''Akodon lactens'' (now ''Necromys lactens'') as a subspecies.〔Musser and Carleton, 2005, p. 1095〕 In 1961, Cabrera listed both ''spegazzinii'' and ''tucumanensis'' as subspecies of ''Akodon boliviensis'', with ''alterus'' as a full synonym of ''A. boliviensis tucumanensis''.〔 In 1990, Philip Myers and colleagues reviewed the ''Akodon boliviensis'' species group. They provisionally kept ''Akodon spegazzinii'' as a species separate from ''A. boliviensis'', with ''tucumanensis'' as a subspecies, and suggested that ''alterus'' was likely related to ''spegazzinii'' and ''tucumanensis''.〔Myers et al., 1990, p. 62〕 Subsequently, the treatment of these species in systematic works became variable. A 1992 paper suggested that ''alterus'' and ''tucumanensis'' were, at best, very similar to each other,〔 but in 1997, Michael Mares and colleagues listed each of the three as distinct species in a compendium of the mammals of Catamarca, citing differences in habitat and fur coloration.〔Mares et al., 1997, pp. 113, 115–116〕 They were followed by Mónica Díaz and Rubén Bárquez in 2007, among others.〔Díaz and Barquez, 2007, pp. 485, 489; Jayat et al., 2010, p. 32〕 However, in 2000 Díaz and colleagues listed ''alterus'' and ''tucumanensis'' as subspecies of ''spegazzinii'' in a review of the mammals of Salta.〔Díaz et al., 2000, p. 24〕 Guy Musser and Michael Carleton, in the 2005 third edition of ''Mammal Species of the World'', also considered the three to represent the same species,〔 as did Ulyses Pardiñas and colleagues in a 2006 review of Argentinean Akodontini.〔Pardiñas et al., 2006, p. 155〕 Meanwhile, Carlos Galliari and Pardiñas had recognized ''Akodon leucolimnaeus'' as a true ''Akodon'', not a ''Necromys'', in 1995. Although associated with the ''Akodon boliviensis'' group, its precise status remained unclear.〔Jayat et al., 2010, p. 32; Musser and Carleton, 2005, p. 1095〕 The common name "Catamarca akodont" was proposed for this species.〔 In 1980, Julio Contreras and María Rosi〔Pardiñas et al., 2011, p. 47〕 identified an ''Akodon'' from the province of Mendoza as ''Akodon varius neocenus'' (now ''Akodon neocenus''), but the following year, they identified it as a new species, named ''Akodon minoprioi'' in a presentation at a scientific meeting. However, this name was never formally validated.〔Braun et al., 2000, p. 216〕 In 2000, Janet Braun and colleagues formally named this species ''Akodon oenos'' and allied it to the ''Akodon varius'' species group. The specific name, ''oenos'', is Greek for "wine" and refers to the animal's occurrence in the wine-producing region of Mendoza.〔Braun et al., 2000, p. 218〕 The common names "Monte akodont"〔Musser and Carleton, 2005, p. 1097〕 and "wine grass mouse"〔Duff and Lawson, 2004〕 were proposed for this species. In 2010, Pablo Jayat and colleagues reviewed the members of the ''Akodon boliviensis'' species group, including ''A. spegazzinii'', in Argentina. They could not find clear differentiation in either morphological or molecular characters between animals belonging to ''A. alterus'', ''A. leucolimnaeus'', ''A. spegazzinii'', and ''A. tucumanensis'', and consequently concluded that they all represent a single species.〔 Although genetic variation is relatively high within ''A. spegazzinii'', there is no clear geographic structure among haplotypes from different regions.〔 The next year, Ulyses Pardiñas and colleagues concluded that ''A. oenos'', which had formerly, and incorrectly, been placed in the ''A. varius'' species group, was in fact another synonym of ''A. spegazzinii''.〔 The proliferation of scientific names for this one species occurred because of the terseness of the original description of ''A. spegazzinii'',〔Jayat et al., 2010, p. 28〕 and a lack of large samples and of appreciation of the substantial variation occurring within ''A. spegazzinii''.〔Jayat et al., 2010, p. 32〕 }} |2= }} }} }} According to phylogenetic analysis of sequences from the mitochondrial cytochrome ''b'' gene, ''Akodon spegazzinii'' is most closely related to ''A. boliviensis'' and more distantly to other members of the ''A. boliviensis'' species group, including ''Akodon polopi'' and ''Akodon sylvanus''.〔 The ''boliviensis'' group is part of the highly diverse genus ''Akodon'' and thereby of the tribe Akodontini, which includes about 90 species of South American rodents. Akodontini is one of several tribes within the subfamily Sigmodontinae and the family Cricetidae, which includes hundreds of mainly small rodents distributed chiefly in Eurasia and the Americas.〔Musser and Carleton, 2005〕 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「Akodon spegazzinii」の詳細全文を読む スポンサード リンク
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