A species of mouse lemur believed to be new to science has been found in the tropical forests of northeastern Madagascar.
Outer morphology of the Jonah’s mouse lemur (Microcebus jonahi), which is named in honor of Malagasy primatologist Professor Jonah Ratsimbazafy, who has dedicated his life’s work to the conservation of Malagasy lemurs: (a) drawing of an adult individual; (b) habitus of adult female; (c-e) close-ups of adult male. Image credit: Stephen D. Nash / IUCN SSC Primate Specialist Group / D. Schüßler.
Madagascar is one of the world’s prime biodiversity hotspots and the lemurs, its endemic group of primates, are flagships for species conservation.
More than 100 species of lemurs are recognized today making up about one-fifth of all living primate species on the Earth.
However, the full extent of lemur species diversity is not yet fully known as several regions in Madagascar are still poorly studied.
Among the most widespread, abundant and adaptable lemurs are the mouse lemurs — small-bodied, omnivorous, nocturnal primates of the genus Microcebus.
These creatures can be found in all regions of Madagascar that offer forested habitats.
They have a combined head, body and tail length of less than 27 cm (11 inches) making them the most diminutive of the primates.
Recognized as two species almost three decades ago, the mouse lemurs now comprise 25 species, largely diagnosed from mtDNA data.
“Many of the new species discovered have been described on the basis of few genetic markers and some scientists have criticized the species inflation, questioning the existence of nearly half of current species but without questioning the extinction risks,” said co-author Dr. Lounès Chikhi, a researcher at the Instituto Gulbenkian de Ciência and the Université Paul Sabatier.
“Instead of a limited number of genetic markers, we resort to genomic, ecological and morphological data, together with several sophisticated methods of inference.”
In the study, Dr. Chikhi and colleagues surveyed communities of mouse lemurs at five different sites in northeastern Madagascar, measuring a variety of morphological parameters and assessing reproductive states for 123 individuals belonging to five different lineages.
“We demonstrated that some of these individuals belong to a divergent lineage, a species never described before,” Dr. Chikhi said.
The newfound species is one of the tiniest primates in the world — it measures about 26 cm (10.2 inches) from nose to tail and has a mass of only 60 grams.
Named the Jonah’s mouse lemur (Microcebus jonahi), it has short and dense reddish-brown fur. The ears are small and are of the same rufous color as the head. The tail is densely furred and of the same coloration as the back. Males and females do not show any sexual dimorphism.
“The Jonah’s mouse lemur can be distinguished from other species in northeastern Madagascar by morphometric features and genomic distinctiveness,” the researchers said.
“Compared with its closest relative, the MacArthur’s mouse lemur (Microcebus macarthurii), the new species is longer, has a shorter tail, wider ears, a larger head width and a shorter head length.”
“In addition, it can be differentiated from the MacArthur’s mouse lemur by its ventral coloration which is rather whitish, but distinctly yellowish orange in the MacArthur’s mouse lemur.”
The Jonah’s mouse lemur inhabits the tropical forests in a small region of northeastern Madagascar.
Out of the 25 captured individuals, six were caught in near-primary forest with a rather continuous canopy and five were captured in highly degraded forests with discontinuous canopy cover and strong regrowth of early successional trees.
“The loss of natural habitats and the constant change in land use in the region lead to the isolation of small populations and this favors their disappearance,” Dr. Chikhi said.
The discovery is described in a paper in the American Journal of Primatology.
_____
D. Schüßler et al. Ecology and morphology of mouse lemurs (Microcebus spp.) in a hotspot of microendemism in northeastern Madagascar, with the description of a new species. Am J Primatol, published online July 27, 2020; doi: 10.1002/ajp.23180
