Neotropical cricetid rodents of the subfamily Sigmodontinae constitute an incredibly diverse and ubiquitous clade of mammals in South America. In spite of recent advances in sigmodontine systematics, a variable collection of genera from eastern South America with no clear tribal affiliations and well-differentiated morphologies has been pervasive in most classification attempts, being generally listed as Sigmodontinae incertae sedis. Here, we assess the phylogenetic relationships of these incertae sedis genera based on supermatrix and multispecies coalescent analyses of a multilocus molecular dataset (one mitochondrial and five nuclear loci) for 76 genera, calibrated with ten fossil-based node dates. Both analytical approaches provided concordant and unprecedented resolution of suprageneric clades within the large Oryzomyalia clade (constituted by most sigmodontine genera), recovering a natural group constituted by the genera Wiedomys , Wilfredomys , and the Atlantic Forest endemics Juliomys and Phaenomys - here redefined as the Wiedomyini tribe - and a sister-relationship between this group and the tribe Abrotrichini. The enigmatic spiny rodent genus Abrawayaomys was recovered as sister to Akodontini in three of four analyses, but pending higher support. Morphological comparisons performed among the four wiedomyine genera highlighted a number of shared external, cranial, and dental similarities useful to emend the tribe diagnosis, such as the presence of chromo-genetic fields associated with the muzzle, pinnae, and rump, the long and narrow rostrum flanked by shallow and narrow zygomatic notches, and the asymmetrically divided procingulum of M1, among other characters. Molecular dating coupled with fossil evidence suggests Wiedomyini as one of the oldest sigmodontine tribes with a late Miocene autochthonous origin in eastern South America, highlighting the relevance of this region as an ancient cradle of sigmodontine lineages.

中文翻译：

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揭开南美洲东部 Sigmodontinae 树（啮齿目：仓鼠科）的深枝

Sigmodontinae 亚科的新热带鼠科啮齿动物构成了南美洲令人难以置信的多样化和无处不在的哺乳动物进化枝。尽管最近在 Sigmodontine 系统学方面取得了进展，但在大多数分类尝试中，来自南美洲东部的没有明确部落隶属关系和良好分化形态的可变属集合普遍存在，通常被列为 Sigmodontinae incertae sedis。在这里，我们基于对 76 个属的多位点分子数据集（一个线粒体和五个核位点）的超矩阵和多物种聚结分析来评估这些 incertae sedis 属的系统发育关系，并使用十个基于化石的节点日期进行校准。两种分析方法都提供了对大型 Oryzomyalia 进化枝（由大多数 sigmodontine 属构成）内的超前进化进化枝的一致且前所未有的解析，恢复了由 Wiedomys 、 Wilfredomys 和大西洋森林特有的 Juliomys 和 Phaenomys 属构成的自然群——这里重新定义为 Wiedomys部落 - 以及这个群体与部落 Abrotrichini 之间的姐妹关系。在四项分析中的三项分析中，神秘的多刺啮齿动物属 Abrawayaomys 作为 Akodontini 的姐妹被发现，但有待更高的支持。在四个 Wiedomyine 属之间进行的形态学比较突出了许多共同的外部、颅骨和牙齿的相似之处，这些相似之处有助于修正部落诊断，例如与口吻、耳廓和臀部相关的染色体遗传场的存在，狭长的喙部两侧是浅而窄的颧骨缺口，以及 M1 的不对称分裂的前体等。分子年代测定和化石证据表明，维多米尼是最古老的西格莫顿部落之一，起源于南美洲东部的中新世晚期本土，突出了该地区作为西格莫顿血统古老摇篮的相关性。