Molecular phylogenetic and taxonomic status of the large-eared desert shrew Notiosorex evotis (Eulipotyphla: Soricidae)

Abstract

Abstract Notiosorex is the only genus of shrews in North America with particular adaptations for arid habitats such as deserts. Five species currently are recognized in the genus, one of which, Notiosorex evotis, lives in deciduous rain forest from northern Sinaloa to the state of Jalisco in México. Notiosorex evotis originally was described as a subspecies of N. crawfordi; however, it was recently proposed as a valid species based on a discriminant function analysis of craniodental characters. Morphological differentiation between N. evotis populations and sympatric occurrences with N. crawfordi in northern Sinaloa have been recognized. Here, we used a phylogenetic analysis of a mitochondrial gene (Cytb; 1,140 bp) and the nuclear beta fibrinogen intron 7 (β-fib I7; 385 bp), as well as cranial geometric morphometrics, to assess the taxonomic status of N. evotis. We found sequences of N. evotis forming two main subclades: one that includes the populations of the state of Sinaloa, the other including populations of Nayarit and Jalisco. The boundaries between the two groups seem to be related to the ecotonal cline between the Pacific Lowlands province and the Trans-Mexican Volcanic Belt province, which acts as a geographical barrier. The discriminant function analysis revealed clear differences in skull shape between the three species of Notiosorex to the northwest of its distribution. Considering these multiple lines of evidence from our data set, we confirm that N. evotis is a monotypic species. Our results suggest that geometric morphometrics can be used successfully to identify sibling species by shape, especially in groups where determination by craniodental measurements is not possible.