Desert shrews of the genus Notiosorex comprise four species with morphological characteristics that are difficult to distinguish among the species. Indeed, N. cockrumi was described using only genetic markers. Based on molecular divergence documented in N. crawfordi, we hypothesize that a fifth species is present in the Baja California peninsula. Genetic variation at the species level was analyzed using individuals from locations west of the Colorado River in the Baja California peninsula, Mexico, and California, United States. Molecular markers of mitochondrial origin (cytochrome b, 1,140 bp; cytochrome c oxidase subunit I, 542 bp; and cytochrome c oxidase subunit III, 672 bp), as well as the nuclear intron 7 of the beta fibrinogen gene (385 bp) were used to construct a phylogeny for species of the genus Notiosorex. Genetic distances of 12.46–15.58% between west and east of the Colorado River were obtained using p-distance models. Our phylogenetic analyses showed almost identical topologies, placing populations from west of the Colorado River in three monophyletic clades with high bootstrap support values. Results of molecular phylogenetic identity among shrews of the genus Notiosorex support the existence of an undescribed, polytypic species of Notiosorex west of the Colorado River.

中文翻译：

---

来自下加利福尼亚半岛和加利福尼亚的沙漠鼩（Notiosorex）的一个新种和三个亚种

Notiosorex 属的沙漠鼩包括四种形态特征难以区分的物种。实际上，仅使用遗传标记描述了科鲁米猪笼草。根据 N. crawfordi 中记录的分子差异，我们假设在下加利福尼亚半岛存在第五个物种。使用来自墨西哥下加利福尼亚半岛和美国加利福尼亚州科罗拉多河以西地区的个体分析物种水平的遗传变异。使用线粒体来源的分子标记（细胞色素 b，1,140 bp；细胞色素 c 氧化酶亚基 I，542 bp；和细胞色素 c 氧化酶亚基 III，672 bp），以及 β 纤维蛋白原基因的核内含子 7（385 bp）构建 Notiosorex 属物种的系统发育。12.46-15 的遗传距离。科罗拉多河西部和东部之间的 58% 是使用 p 距离模型获得的。我们的系统发育分析显示了几乎相同的拓扑结构，将来自科罗拉多河以西的种群置于三个具有高引导支持值的单系进化枝中。Notiosorex 属鼩鼱的分子系统发育同一性的结果支持在科罗拉多河以西存在未描述的多型 Notiosorex 物种。