Ganzhorna's mouse lemur (Microcebus ganzhorni). The IUCN Red List of Threatened Species 2020

Abstract

Up to 2016, the south-eastern subpopulation of Grey Mouse Lemurs has been considered to represent a disjunct population of Microcebus murinus (Mittermeier et al. 2010). Based on samples from the littoral forest of Mandena a new form has been separated from M. murinus and been named as M. ganzhorni based on genetic grounds (Hotaling et al. 2016). Morphologically M. ganzhorni is indistinguishable from M. murinus and difficult to distinguish from M. griseorufus (M. griseorufus has a white belly with white underfur while M. murinus and M. ganzhorni have greyish underfur) and thus, taxonomic assignments in the field remain uncertain without genetic analyses. Given these uncertainty, the Extent of Occurrence was unclear at the time the species was described. New genetic analyses showed that M. ganzhorni does not occur in Andohahela National Park (Tiley, Poelstra, Yoder et al., unpubl. data) and does not move up the coastal mountains as this is the range of M. tanosi and M. manitatra (Rasoloarison et al. 2013, Donati et al. 2019). M. ganzhorni thus seems to be restricted to littoral forests east and possibly west of Fort Dauphin. In any case, the area of occupancy (AOO) is estimated to be above 10 km� but below 500 km�. These forests are severely fragmented with the largest fragments measuring less than 2 km�. The size of most forest fragments is declining and forests are being degraded. The species tolerates forest degradation and occurs in a wide range of different habitats, including gardens....