First indications of a highland specialist among mouse lemurs (Microcebus spp.) and evidence for a new mouse lemur species from eastern Madagascar.

The factors that limit the distribution of the highly diverse lemur fauna of Madagascar are still debated. We visited an understudied region of eastern Madagascar, a lowland rainforest site (Sahafina, 29-230 m a.s.l.) close to the Mantadia National Park, in order to conduct a survey and collect further distributional data on mouse lemurs. We captured, measured, photographed, and sampled mouse lemurs from the Sahafina forest, performed standard phylogenetic methods based on three mitochondrial DNA genes, and conducted morphometric comparisons in order to clarify their phylogenetic position and taxonomic status. The mouse lemurs from the Sahafina forest could not be assigned to any of the known mouse lemur species and were highly divergent in all molecular analyses from all previously described species. Since they also differed morphometrically from their sister species and from their geographic neighbors, we propose species status and include a species description at the end. This study suggests that M. lehilahytsara may be the first highland specialist among all mouse lemurs. The distribution of the newly described mouse lemur is not fully known, but seems to be rather restricted and highly fragmented, which raises serious conservation concerns.