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''Euryoryzomys emmonsae'', also known as Emmons's Rice Rat〔 or Emmons' Oryzomys,〔Musser and Carleton, 2005, p. 1148〕 is a rodent from Amazonian Brazil in the genus ''Euryoryzomys'' of the family Cricetidae. Initially misidentified as ''E. macconnelli'' or ''E. nitidus'', it was formally described in 1998. A rainforest species, it may be scansorial, climbing but also spending time on the ground. It occurs only in a limited area south of the Amazon River in the state of Pará, a distribution that is apparently unique among the muroid rodents of the region. ''Euryoryzomys emmonsae'' is a relatively large rice rat, weighing 46 to 78 g (1.6 to 2.8 oz), with a distinctly long tail and relatively long, tawny brown fur. The skull is slender and the incisive foramina (openings in the bone of the palate) are broad. The animal has 80 chromosomes and its karyotype is similar to that of other ''Euryoryzomys''. Its conservation status is assessed as "Data Deficient", but deforestation may pose a threat to this species. ==Taxonomy== In 1998, Guy Musser, Michael Carleton, Eric Brothers, and Alfred Gardner reviewed the taxonomy of species previously lumped under "''Oryzomys capito''" (now classified in the genera ''Hylaeamys'', ''Euryoryzomys'', and ''Transandinomys''). They described the new species ''Oryzomys emmonsae'' on the basis of 17 specimens from three locations in the state of Pará in northern Brazil; these animals had been previously identified as ''Oryzomys macconnelli'' (now ''Euryoryzomys macconnelli'') and then as ''Oryzomys nitidus'' (now ''Euryoryzomys nitidus'').〔 The specific name honors Louise H. Emmons, who, among other contributions to Neotropical mammalogy, collected three of the known examples of the species in 1986, including the holotype.〔Musser et al., 1998, pp. 233, 239〕 The new species was placed in what they termed the "''Oryzomys nitidus'' group", which also included ''O. macconelli'', ''O. nitidus'', and ''O. russatus''.〔Musser et al., 1998, p. 175〕 In 2000, James Patton, Maria da Silva, and Jay Malcolm reported on mammals collected at the Rio Juruá in western Brazil. In this report, they provided further information on the ''Oryzomys'' species reviewed by Musser and colleagues, including sequence data from the mitochondrial cytochrome ''b'' gene. Their analysis reaffirmed that ''O. emmonsae'' was a distinct species and found that it was closest to ''O. macconnelli'' and ''O. russatus'', differing from both by about 12% in the cytochrome ''b'' sequence; ''O. nitidus'' was more distantly related, differing by 14.7%. The average sequence difference between the three ''O. emmonsae'' studied was 0.8%.〔Patton et al., 2000, fig. 99; table 37〕 In 2006, an extensive morphological and molecular phylogenetic analysis by Marcelo Weksler showed that species then placed in the genus ''Oryzomys'' did not form a single, cohesive (monophyletic) group; for example, ''O. macconnelli'', ''O. lamia'' (placed under ''O. russatus'' by Musser and colleagues) and ''O. russatus'' clustered together in a single natural group (clade), but were not closely related to the type species of ''Oryzomys'', the marsh rice rat (''O. palustris'').〔Weksler, 2006, figs. 34–39〕 Later in 2006, Weksler and colleagues described several new genera to accommodate species previously placed in ''Oryzomys'', among which was ''Euryoryzomys'' for the "''O. nitidus'' complex", including ''O. emmonsae''.〔Weksler et al., 2006, p. 11〕 Thus, the species is now known as ''Euryoryzomys emmonsae''.〔 As a species of ''Euryoryzomys'', it is classified within the tribe Oryzomyini ("rice rats"), which includes over a hundred species, mainly from South and Central America.〔Weksler et al., 2006, table 1; Musser and Carleton, 2005〕 Oryzomyini in turn is part of the subfamily Sigmodontinae of family Cricetidae, along with hundreds of other species of mainly small rodents.〔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「Euryoryzomys emmonsae」の詳細全文を読む スポンサード リンク
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