Phylogenetic relationships in the genus Aethomys (Rodentia: Muridae)

Abstract

Phylogenetic relationships in the genus Aethomys were examined based on qualitative cranial data for all currently recognized species. A cladistic analysis suggested the presence of three clades: 1) A. bocagei, A. thomasi, A. silindensis, A. kaiseri, and A. nyikae;2) A. chrysophilus, A. ineptus, and A. hindei;3) A. granti, A. namaquensis, and A. stannarius. These phylogenetic groupings are largely inconsistent with previously postulated supraspecific relationships for the genus. Nonetheless, relationships within each clade broadly correspond with some previously suggested evolutionary hypotheses among some members of the genus, the only notable exception being a close affinity between two southern African taxa (A. namaquensis and A. granti) and the geographically disjunct West African endemic, A. stannarius. A phylogram derived from an analysis of anagenetic divergence among taxa supported the widely-held view of a close affinity between A. namaquensis and A. granti that has traditionally led to their inclusion in the subgenus Micaelamys. These results are relatively concordant with recent molecular studies based on microcomplement fixation of albumin, mitochondrial DNA cytochrome b and 16S rRNA data, which collectively suggest that the genus Aethomys is paraphyletic. Possible paraphyly is also reflected by a relatively low bootstrap value at the node uniting all ingroup taxa in this study, as well as previous studies on dental morphology, modes of karyotypic change, and gross sperm and bacular morphology, and strongly supports the taxo-nomic elevation of the currently recognized subgenera Micaelamys and Aethomys to full generic rank. Despite the broad correspondence between the morphological and molecular data, homoplasy and low bootstrap support in the present investigation point to the need for a careful consideration of the power and choice of morphological characters in future studies on this and related groups of murine rodents.

Keywords: Aethomys, cladistics, anagenetic divergence, qualitative cranial morphology,systematics