A team of biologists led by Professor Anna Nekaris of Oxford Brookes University in the UK, and Rachel Munds from the University of Missouri in Columbia, studied slow lorises in Borneo and the Philippines and discovered what they thought was one species are actually four different ones, all with different facial markings.
Originally there was thought to be just a single species, called N. menagensis.
Two of these new species, N. bancanus and N. borneanus, were previously considered subspecies of N. menagensis.
While, N. kayan, is new to science.
"In Borneo in particular, from where three of the new species hail, this will mean that three new lorises will be added as threatened to some degree on the IUCN Red List of threatened species," says Prof Nekaris.
"With more than 40% of the world's primates already threatened with extinction, this brings the toll even higher."
Outside of Borneo and the Philippines, four other slow loris species are known, living across south and southeast Asia.