SYSTEMATICS OF ARVICANTHIS (RODENTIA, MURIDAE) FROM THE HORN OF AFRICA - A GEOMETRIC MORPHOMETRICS EVALUATION

Changes in size and shape in the skull of five species of the African rodent genus Arvicanthis were studied using Geometric Morphometrics, i n an attempt to evaluate their systematics and taxonomy which is still confused. Four species endemic to the Horn of Africa (A. abyssinicus, A. dembeensis, A. blicki and A. somalicus) and a population of the 'A . niloticus' complex from West Africa (Benin) were investigated. These species are widespread with ranges at very different altitudes, from arid grasslands up to the alpine moorlands at 4300 m a.s.l., and repre sent one of the major pests in croplands. Size and shape differences b etween species were compared with phylogeny (deduced from karyotype re arrangements), time of divergence (allozymes) and altitude. Morphometr ic divergence does not reflect any cladogenetic sequence and neither a ny association with altitude, but rather adaptive patterns that are un ique to each species.