Carrión-Olmedo Julio C, Brito Jorge
Instituto Nacional de Biodiversidad, Quito, Ecuador.
PeerJ. 2025 Jul 10;13:e19648. doi: 10.7717/peerj.19648. eCollection 2025.
The shrew-opposums of the genus (Thomas, 1895) belong to a group of Ameridelphian marsupial mammals in the order Paucituberculata, an order in which most of its representatives are extinct. This genus contains five formally described species: , and , all with type localities in Ecuador, plus at least three candidate species from Colombia now recognized as subspecies , and . Records of this genus are not abundant, both in biological collections and in sequence repositories (GenBank); thus, showing a discontinuous geographical distribution that could be a consequence of incomplete sampling. Systematic expeditions by the Instituto Nacional de Biodiversidad (INABIO) have increased the geographic sampling of this genus in Ecuador, which allowed us to reevaluate its genetic diversity. We obtained 43 sequences of cyt and 30 of RAG1 from 28 Ecuadorian localities in 12 Provinces, including novel topotypical material from , , and . We present a new hypothesis on the genetic diversity of using maximum likelihood inference for phylogenetic analysis, estimate genetic distances and divergence times for the genus. We found a species complex in the clade, with at least three candidate new species, having a threshold above 5% for the estimated genetic distance of the cyt among them. Also, we found two additional lineages hidden within . We expect that future work, with similar or larger sampling efforts in Colombia and Peru would reveal greater phylogenetic diversity and more complete evolutionary relationships.
（托马斯，1895年）属的鼩负鼠属于袋鼬目美洲有袋类哺乳动物，该目大多数代表物种已灭绝。该属包含五个正式描述的物种： 、 、 、 和 ，所有物种的模式产地均在厄瓜多尔，另外还有来自哥伦比亚的至少三个候选物种，现在被认定为亚种 、 和 。无论是在生物样本库还是序列数据库（GenBank）中，该属的记录都不丰富；因此，其地理分布呈现间断性，这可能是采样不完整的结果。厄瓜多尔国家生物多样性研究所（INABIO）的系统考察增加了该属在厄瓜多尔的地理采样，这使我们能够重新评估其遗传多样性。我们从12个省份的28个厄瓜多尔地点获得了43条细胞色素b（cyt）序列和30条重组激活基因1（RAG1）序列，包括来自 、 和 的新的模式产地材料。我们利用最大似然推断进行系统发育分析，提出了一个关于该属遗传多样性的新假设，估计了该属的遗传距离和分歧时间。我们在该进化枝中发现了一个物种复合体，至少有三个候选新物种，它们之间细胞色素b估计遗传距离的阈值高于5%。此外，我们还在 中发现了另外两个隐藏的谱系。我们预计，未来在哥伦比亚和秘鲁进行类似或更大规模采样的工作将揭示出更大的系统发育多样性和更完整的进化关系。
