Phylogeny of Acomys spinosissimus (Rodentia, Muridae) from north Malawi and Tanzania: evidence from morphological and molecular analysis

New specimens of Acomys spinosissimus from northern Malawi and southern Tanzania were subjected to morphological, molecular (cytochrome b mitochondrial gene) and cytogenetical analysis in order to establish the phylogenetic position of these populations among A. spinosissimus, as well as their relationships with other species (A. subspinosus and A. wilsoni). The monophyly of the spinosissimus clade is supported by morphological and molecular phylogenies. Cytogenetics and morphology, but not the cytochrome b phylogeny show the possible existence of two sibling species within spinosissimus. Incongruences are noted between molecular and morphological trees, especially concerning the position of the Transvaal specimens. Two different biogeographic scenarios for the origin and dispersal of A. spinosissimus are discussed in the light of available palaeontological data.