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<p>Neotropical rodents of the genus <i>Thrichomys</i> inhabit open vegetation biomes, including the Brazilian Caatinga, Cerrado, and Pantanal, as well as the Paraguayan and Bolivian Chaco regions. For a long time, this genus was considered monospecific until karyotypic and phylogenetic studies revealed its high diversity. Nevertheless, its taxonomy remains complex, and the exact number of species within <i>Thrichomys</i> is still not well established. In particular, there are unresolved questions regarding the taxa <i>T. pachyurus</i> and <i>T. fosteri</i>. To address this taxonomic problem, we conducted an integrative analysis combining karyotypic, morphological, and molecular data. Our findings confirmed that <i>T. pachyurus</i> and <i>T. fosteri</i> are distinct species and clarified the correct associations between these nominal forms and their karyotypes, 2n = 30, FNa = 56 and 2n = 34, FNa = 64, respectively. The morphological analysis of the <i>T. pachyurus</i> type series and new topotypic material allowed the definitive linkage of the name <i>pachyurus</i> to the 2n = 30 karyomorphotype. Additionally, we described a new <i>Thrichomys</i> species, which exhibits a novel karyotype for the genus (2n = 48, FNa = 84), as well as unique cranial traits such as the presence of premaxillary pits. Phylogenetic analyses using mitochondrial (mt-Cytb) and nuclear (Fgb-I7) markers revealed that the new species represents the earliest diverging lineage within <i>Thrichomys</i>, thus contributing critical insight into the evolutionary history of the genus. The new species appears to be restricted to rocky outcrops habitats in the western portion of the Brazilian Cerrado. This study also presents the first documented case of sympatry within <i>Thrichomys</i>, with <i>T. pachyurus</i> and <i>Thrichomys</i> sp. nov. captured on the same trap lines.</p>

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The hidden diversity in Thrichomys Trouessart, 1880 (Rodentia: Echimyidae): identity of T. pachyurus (Wagner 1845), and the description of a new species from Central Brazil

  • 期刊论文

  • 发表日期：

    2025年10月3日

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  • Ana Lazar,
  • Marcelo Weksler,
  • Cibele R. Bonvicino

摘要

Neotropical rodents of the genus Thrichomys inhabit open vegetation biomes, including the Brazilian Caatinga, Cerrado, and Pantanal, as well as the Paraguayan and Bolivian Chaco regions. For a long time, this genus was considered monospecific until karyotypic and phylogenetic studies revealed its high diversity. Nevertheless, its taxonomy remains complex, and the exact number of species within Thrichomys is still not well established. In particular, there are unresolved questions regarding the taxa T. pachyurus and T. fosteri. To address this taxonomic problem, we conducted an integrative analysis combining karyotypic, morphological, and molecular data. Our findings confirmed that T. pachyurus and T. fosteri are distinct species and clarified the correct associations between these nominal forms and their karyotypes, 2n = 30, FNa = 56 and 2n = 34, FNa = 64, respectively. The morphological analysis of the T. pachyurus type series and new topotypic material allowed the definitive linkage of the name pachyurus to the 2n = 30 karyomorphotype. Additionally, we described a new Thrichomys species, which exhibits a novel karyotype for the genus (2n = 48, FNa = 84), as well as unique cranial traits such as the presence of premaxillary pits. Phylogenetic analyses using mitochondrial (mt-Cytb) and nuclear (Fgb-I7) markers revealed that the new species represents the earliest diverging lineage within Thrichomys, thus contributing critical insight into the evolutionary history of the genus. The new species appears to be restricted to rocky outcrops habitats in the western portion of the Brazilian Cerrado. This study also presents the first documented case of sympatry within Thrichomys, with T. pachyurus and Thrichomys sp. nov. captured on the same trap lines.