A New Species of Margaretamys (Rodentia: Muridae: Murinae: Rattini) from Pegunungan Mekongga, Southeastern Sulawesi, Indonesia.

Margaretamys christinae n. sp. is described from an adult male collected in tropical lower montane rain forest in Pegunungan Mekongga, the most extensive mountainous region on the southeastern peninsula of Sulawesi. Physical characteristics of the specimen (body size, fur coloration and texture, and dimensions of appendages) along with cranial and dental qualitative and quantitative aspects are contrasted with similar traits in samples of M. beccarii (Musser, 1981), M. elegans (Musser, 1981), and M. parvus (Musser, 1981), the three other described species in the genus. The new species joins M. elegans and M. parvus as representatives of montane endemics, the former in Pegunungan Mekongga, the latter two in the west-central mountain block of Sulawesi's core; M. beccarii occupies habitats in tropical lowland evergreen rain forest and is known by voucher material from the northeastern tip of the northern peninsula and central Sulawesi. Aside from its capture site 1.5m above ground at 1537m in lower montane forest, its age and sex, no other ecological information exists for the Mekongga species, but its possible if not probable ecology is inferred from ecological information associated with the three other species. The four species are also the subjects of short discussions covering sympatry, zoogeography, phylogenetic alliances, and conservation.