Phylogeny, biogeography, and integrative taxonomic revision of the Afro-Arabian rodent genus Ochromyscus (Muridae: Murinae: Praomyini)

The analyses of Plio-Pleistocene speciation processes in the Horn of Africa are relevant for understanding the evolution of biodiversity patterns of this understudied part of the world. Here we analyse comprehensive genomic and morphological data of the recently delimited murid genus Ochromyscus, one of the few with Afro-Arabian distribution. Using an integrative taxonomic approach, we delimit three species in the genus: two in eastern Africa (O. brockmani and O. niveiventris) and one in southern Arabia (O. yemeni), and detail their distribution, genetic structure, and evolutionary history. Despite their morphological similarity, the three species split before the Pleistocene, and their interspecific genetic divergence level is comparable to that between sister genera of murine rodents. The split between two taxa living on opposite sides of the Red Sea (O. brockmani vs. O. yemeni) is younger than the separation of their ancestor and O. niveiventris living in eastern Africa. The colonization of Arabia can be explained either by the presence of a relatively recent continental bridge or by the past occurrence of the genus along the eastern coast of the Red Sea and subsequent spreading through the Sinai Peninsula.