We present a new assessment of the genetic and morphological variation within Oxymycterus quaestor Thomas, 1903, which currently includes the junior synonyms O. judex Thomas, 1909 and O. misionalis Sanborn, 1931. We integrate distinct lines of evidence, including variation of mitochondrial (Cytochrome b [Cytb]) and nuclear (intron 7 of beta fibrinogen gene [Fgb]) sequences, and the assessment of skull quantitative traits based on geometric morphometrics, throughout the Atlantic Forest of Southeastern-Southern Brazil, Argentina, and Paraguay. Phylogenetic relationships based on Cytb indicate that O. quaestor is structured in four well-supported clades (lineages A–D), one of them (lineage C) including topotypes of a previously associated nominal form (O. judex). However, these Cytb lineages exhibit lower levels of differentiation based on the Fgb locus, and are not recovered in the genealogies of this nuclear marker, representing a case of mitonuclear discordance. The Cytb lineages also broadly overlapped in the morphospace both in skull shape and size, which sustain the current wider concept of O. quaestor as one single young species (0.947 Myr) that is recently expanding, and ultimately branching out, in the Atlantic Forest.

中文翻译：

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巴西大西洋森林中Oxymycterus（Rodentia：Sigmodontinae）的遗传和形态变异

我们提出了一种新的评估，即Oxymycterus quaestor Thomas，1903年内的遗传和形态变异，该评估目前包括初级同义词O. judex Thomas，1909年和O. misionalis Sanborn，1931年。我们整合了不同的证据，包括线粒体（在巴西东南部南部，巴西，阿根廷和巴拉圭的大西洋森林中，发现了细胞色素b [ Cytb ]）和核（β纤维蛋白原基因[ Fgb ]的内含子7 ）序列，并基于几何形态计量学对头骨的定量性状进行了评估。基于Cytb的系统发生关系表明O. quaestor由四个支撑良好的进化枝（A-D谱系）构成，其中一个进化谱（C谱系）包括先前关联的标称形式（O. judex）的拓扑类型。但是，这些Cytb谱系在Fgb基因座的基础上显示出较低的分化水平，并且在该核标记物的谱系中未得到恢复，这代表了小核不和谐。的细胞色素b谱系还广泛地在无论是在颅骨的形状和尺寸的morphospace，其维持的当前更宽的概念重叠O.财务官为一个单一年轻的物种（0.947 MYR）是最近扩展，最终分支出来，在大西洋森林。