Ethiopian rats (genus Stenocephalemys) represent a monophyletic group of Ethiopian endemic rodents that diverged in the Ethiopian Highlands during the Pleistocene. Because of the frequent occurrence of so-called reticulate evolution (i.e. repeated hybridization of partially diverged populations), their taxonomy has not been adequately resolved, despite the fact that they belong to the most abundant rodent genus in Ethiopia and are important as pests and carriers of pathogens (e.g. hantaviruses). Here we analysed material for 623 Stenocephalemys specimens using integrative taxonomy composed of genomic analyses (388 nuclear markers and complete mitogenomes), 2D-geometric morphometry of skulls and classical morphometry of external traits. The genus consists of six clearly defined gene pools (= species), characterized by specific morphology, ecology and distribution. Two of them, described here as new species, live in fragmented populations in Afroalpine habitats in the north-western part of the Ethiopian Highlands. We also showed that mitochondrial DNA is not applicable as a universal diagnostic tool for species discrimination in Stenocephalemys, because of multiple cases of mitochondrial introgression. This finding illustrates the utility of the genus as a suitable model for future studies of mito-nuclear coevolution along an elevational gradient.
We describe two new species of white-toothed shrews from south-western and central Ethiopia, based on recent collections and an application of morphological and genetic methods, Crocidura similiturba sp. nov. and Crocidura makeda sp. nov. Comparisons are provided with other Crocidura species known to occur in the country. Both new species are currently known only from the Ethiopian Highlands. Furthermore, we provide new geographical records and discuss biogeographical patterns in the country. New molecular data, even if based primarily on mitochondrial cytochrome b, suggests substantial divergence within afrotropical Suncus megalura, suggesting that the East African lineage might be considered separated at the species level – Suncus sorella (Thomas, 1897), stat. nov. Molecular data support a monophyly of the clade, grouping most Crocidura species endemic to Ethiopia (the East African subclade of the Old World clade), but also indicates additional colonisations of Ethiopian Plateau from East and Central Africa in the past. The remarkable number of endemics shows that Ethiopia is an important centre for the Crocidura radiation, as is the case for other groups of non-flying terrestrial vertebrates.