The world's newest monkey species was found in a lab, not on an expedition

The discovery of the Popa langur, a medium-sized leaf-eating monkey found in central Myanmar, was recently announced by scientists. It is estimated there are just 200 to 250 of these monkeys, which will likely mean the new species is classed as "critically endangered." This find was announced just a week or so after two new species of greater glider – a gliding marsupial – were identified in Australia. But what do scientists mean when they announce the discovery of "new" mammalian species? Were these animals really unknown to science?

While discoveries such as the langur and the gliders are certainly exciting, it is important to clarify that these were not previously unseen species uncovered by some intrepid explorer. Rather, these animals have been identified as a genetically distinct group within an already-known population. In fact, local people have been living with these animals for generations, and have their own ways of identifying and classifying species. When scholars announce a newly defined species based on genetic evidence, it usually means they have elevated an already defined subspecies to the species level.

Species are not as clear-cut as they seemed when we first learned about them in school. Most scholars use the “biological species concept”, which is based on whether the animals are able to produce fertile offspring together, but there are many other ways to define a species. Like most other recently-described primates, the Popa langur has been identified using genetic information, or the phylogenetic species concept. This is based on how animals relate to other groups in evolutionary terms, essentially defining a species as the smallest group that can be genetically distinguished from another species but still shares a clear ancestor.

Elevation of a subspecies to new species based on genetic information can be controversial. Some scholars dismiss these discoveries as “taxonomic inflation”, and worry that changing classifications can confuse conservation efforts. Others note that without a name and reliable population estimate, these little pockets of genetic variation could easily go extinct without notice, and that elevating them to species level ensures that conservation funding and efforts are directed to these at-risk groups. Wherever you stand, it is worth noting that the idea of a species – under any definition – is a human construct to explain variation in the natural world, and no definition will be a perfect representation of biological variation.