Abstract:
Five species of African rock rats of the genus Aethomys, A.namaquensis, A. granti, A. silindensis, A. chrysophilus and A. ineptus, are recognized in southern Africa. Morphometric analyses indicated that A. namaquensis, A. granti and A. silindensis differ markedly in cranial size and/or shape. Morphometric analyses involving cytogenetically known specimens of A. chrysophil us revealed the presence of two sympatric, morphologically similar species, A. chrysophilus and A. ineptus. This is in agreement with observations on cranial morphology and earlier investigations involving cytogenetics, protein electrophoresis and sperm morphology. Contrary to published reports, the morphometric data show that the Central African A. nyikae does not occur in southern Africa, and the single previous record from eastern Zimbabwe is probably based on a misidentification. Four subspecies, A. n. namaquensis, A. n. lehocla, A. n. alborarius and A. n. monticularis, which broadly coincide with major biomes of southern Africa, are recognized within A. namaquensis. Two subspecies, A. c. chrysophilus and A. c. imago, which broadly coincide with altitudinal limits of the eastern part of southern Africa, are recognized within A. chrysophilus. Intraspecific variation in A. ineptus is clinal, with size positively and significantly correlated with longitude. Variation within the geographically restricted A. granti suggests a southwesterly-northeasterly cline. A cladistic appraisal of phylogenetic relationships among the 11 recognized species of Aethomys in Africa, based on qualitative cranial characters, suggests the retention of Micaelamys and Aethomys as subgenera.
