‘These are “cryptic” species,’ says Dr Scott Hotaling, biologist at the University of Kentucky, ‘which means that they look the same as other species but are genetically distinct. They cannot interbreed.’
The new additions to the list of Earth’s species are three types of mouse lemur, Microcebus ganzhorni, Microcebus manitatra and Microcebus boraha. They are small, some no bigger than the palm of a human hand, and their similar looks have allowed them to blend in with a deceptively large population of other mouse lemurs. By sampling 16 individuals, Hotaling and researchers from the University of Kentucky realised they had stumbled across three completely distinct species.
‘Mouse lemurs are the most speciose genus of lemurs,’ says Dr Peter Kappeler of the German Primate Centre who co-discovered them. Just 20 years ago, there were only two species of mouse lemurs known to science. Now there are 24. ‘Because they live all over the island, they are an excellent model system to reconstruct the colonisation of Madagascar and the dynamics of the adaptive radiation – where multiple species evolve from a common ancestor.’
There is an urgency to discovering any more that may be living in the Madagascan canopies – habitats that are increasingly encroached by agricultural and urban development. According to the International Union for Conservation of Nature Red List, lemurs are among the most threatened vertebrae in the world, with 94 per cent threatened with extinction. ‘We need to explore forests for more species before they disappear, as well as protect those that have just been discovered,’ says Kappeler. ‘We still know nothing about their ecology or social systems.’ Increased development risks missing some pieces of the puzzle.
Hotaling, however, believes the lemurs’ species diversity is crucial to their conservation: ‘One species might appear to be wide-ranging with high numbers but in reality there may be four species, which all have much smaller population sizes and ranges and do not interbreed,’ he says, ‘in which case, the conservation story is a much different and potentially more dire one. By understanding the biodiversity of Madagascar, and specifically of imperilled primates like the mouse lemurs, we are better able to define units for conservation focus and protect what is already there.’