(CNN)Scientists have discovered a new primate species in the jungles of Myanmar -- and it's already at risk of extinction.
The Popa langur is a type of monkey with a long tail, rings around its eyes, and a crest of fur on top of its head. There are only an estimated 200 to 260 left, according to a news release by the London Natural History Museum, which collaborated on this study.
The research team named the Popa langurs after the sacred extinct volcano Mount Popa and classified them as "critically endangered."
"Sadly this is a bittersweet discovery due to the limited number of individuals left in the wild and fragmented populations," said Roberto Portela Miguez, a senior curator at the Natural History Museum, in the release.
"The hope is that by giving this species the scientific status and notoriety it merits, there will be even more concerted efforts in protecting this area and the few other remaining populations."
The scientists, spanning three organizations, published their findings on Wednesday in the journal Zoological Research.
In the study, researchers at Fauna and Floral International (FFI) and the German Primate Center (GMC) carried out field surveys of the langurs, whose scientific name is "Trachypithecus popa." They also gathered samples and DNA of all other Trachypithecus species -- cousins of the Popa langur.
They combined the data from these surveys and samples, as well as data from specimens in other museums, confirm the existence of the new species, said the news release.
One of the crucial parts of the puzzle was a 100-year-old specimen that had been stored at the London Natural History Museum. In the early 20th century, British zoologist Guy C. Shortridge collected thousands of specimens, including a 1913 Trachypithecus specimen that the Popa langur team re-examined.
"Monkeys are one of the most iconic groups of mammals, and these specimens have been in the collections for over a hundred years," said Miguez. "But we didn't have the tools or the expertise to do this work before."
There were other clues that the Popa langur was an entirely new species, like differences in its tail length, fur color, and skull shape -- but genetic analysis confirmed it.
"This study demonstrates that natural history collections are a valuable and key resource for genetic research and in the context of the current biodiversity crisis, they are clearly even more relevant and important today than ever before," said Miguez.
The Popa langurs were likely once widespread across central Myanmar, according to the study, which analyzed historical records like museum specimens and travel notes -- but only a few groups survived. Now, the remaining individuals only live in four isolated populations.
The largest population is on Mount Popa, home to more than 100 langurs. Mount Popa, a sacred pilgrimage site, is also home to an important wildlife sanctuary -- but threats remain for the endangered Popa langurs.
"Although Mount Popa is a national park, meaning the species that occur there are legally protected, hunting and deforestation for the timber industry and fuelwood still occur," said Miguez.
Other threats include agricultural encroachment, environmental degradation, and other disturbances to the land like free cattle grazing, said the study.
The study urged international agencies like the International Union for Conservation of Nature (IUCN) and the Convention on International Trade in Endangered Species (CITES) to add the Popa langur to their lists of threatened species.
"Improved protected area management, in particular improved law enforcement ... is essential to stabilize the two largest known populations," said the study. "The forests in Bago Yoma are severely degraded and fragmented, but could still provide the largest, contiguous habitat if deforestation and forest degradation are reversed through improved forest protection and restoration."