A new mouse lemur: Microcebus ganzhorni

The Latin word lemures means "ghost." Malagasy people have traditionally associated these primates with spirits because they are active at night, and perhaps because of their eerie, large-eyed stare. The mouse lemurs live in forests usually in a small female-led group.

Mouse lemurs live in the South and East of Madagascar. As little as 20 years ago, only two species of these small, nocturnal primates were known. The new study that describes our species of the day brings the count of species up to 24 and as all other lemurs they only occur on Madagascar.

The new species was named in honor of the German ecologist Prof. Jörg Ganzhorn who works on ecology and conservation in Madagascar for more than thirty years.

For the experts: Implementation of the coalescent model in a Bayesian framework is an emerging strength in genetically-based species delimitation studies. By providing an objective measure of species diagnosis, these methods represent a quantitative enhancement to the analysis of multi-locus data, and complement more traditional methods based on phenotypic and ecological characteristics. Recognized as two species 20 years ago, mouse lemurs (genus Microcebus) now comprise more than 20 species, largely diagnosed from mtDNA sequence data. With each new species description, enthusiasm has been tempered with scientific skepticism. Here, we present a statistically justified and unbiased Bayesian approach towards mouse lemur species delimitation. We perform validation tests using multi-locus sequence data and two methodologies: (1) reverse-jump Markov chain Monte Carlo sampling to assess the likelihood of different models defined a priori by a guide tree, and (2) a Bayes factor delimitation test that compares different species-tree models without a guide tree. We assess the sensitivity of these methods using randomized individual assignments, which has been used in BPP studies, but not with Bayes factor delimitation tests. Our results validate previously diagnosed taxa, as well as new species hypotheses, resulting in support for three new mouse lemur species. As the challenge of multiple researchers using differing criteria to describe diversity is not unique to Microcebus, the methods used here have significant potential for clarifying diversity in other taxonomic groups. We echo Carstens et al. (2013) in advocating that multiple lines of evidence, including use of the coalescent model, should be trusted to delimit new species.