There are 52 species of flying squirrels in the world. The little nocturnal omnivores inhabit most of Earth's forests, including those along eastern North America. But even under the best of circumstances catching a glimpse of the creatures, which use specialized flaps of skin to glide from tree to tree, is difficult. In fact, the animals are so hard to observe, scientists are still finding new ones. The most recent, Biswamoyopterus gaoligongensis, or the Mount Gaoligong flying squirrel, was recently found in the forests of Yunnan Province in Southwest China and described in the journal ZooKeys.

According to a press release, flying squirrels in the genus Biswamoyopterus are the rarest and most mysterious. The first species in the group, the Namdapha flying squirrel, was described in 1981 and is known from only a single specimen collected in India's Namdapha National Park. It has not been seen since. The Laotian flying squirrel was found only in 2013, also from a single creature—one being sold as part of the bushmeat trade. Both animals are pretty large for squirrels, weighing in between 3 and 4 pounds.

So Quan Li of the Kunming Institute of Zoology at the Chinese Academy of Sciences was surprised last year when he came across a Biswamoyopterus squirrel in the Academy’s collection. At first, he believed it was a rare second specimen of the Namdapha squirrel. But closer examination revealed it was quite different. Not only was its coloration dissimilar, but its teeth and other details of its anatomy were distinguishable from the other two species.

“The morphological features of B. gaoligongensis are closer to the critically endangered and missing Namdapha flying squirrel, but is still readily identifiable as a distinct species,” Quan Li says in the release.

According to the paper, unlike the other two species, the ear tufts of the large squirrel are bicolored and the scrotum of males is dark brown, contrasting with its white belly. Its skull is also shorter and wider than other members of its genus.

To learn more about the new species, a field team traveled to the spot in the Gaoligong Mountains near southwestern China's border with Myanmar to explore the area where the original was captured. They were able to gather another specimen of the squirrel and observed two others gliding through the canopy in two other nearby areas, one six miles west and the other six miles to the south.

George Dvorsky at Gizmodo reports that the new species answers the mystery of why the two previously discovered Biswamoyopterus are so closely related but separated by hundreds of miles—they may not be. In addition to B. gaoligongensis, there could be other undiscovered flying squirrels connecting the distant populations.

“The new species was discovered in the ‘blank area’ spanning 1,250 km [776 miles] between the isolated habitats of the two known species, which suggests that the genus is much more widespread than previously thought,” Quan Li says in the release. “There is still hope for new Biswamoyopterus populations to be discovered in between or right next to the already known localities.”

Dvorsky reports that genetic testing has not been conducted on the species. Besides its morphology, researchers don’t know much about it, except that it prefers low-altitude forests, lives by rivers and, like all flying squirrels, loves the night life.

But its preference for lowland forest, which are close to human settlement, means the species—perhaps within the realm of qualifying for the endangered list—is already facing some major threats, including the slow creep of agriculture into the area and potential poaching. “Therefore, there is an urgent need to study the ecology, distribution, and conservation status of this rare and very beautiful genus,” Quan Li said in the release.

The Chinese flying squirrel isn’t the only rodent recently added to the tree of life. Just last month researchers described two new species of tweezer-beaked hopping rats discovered in the Philippines.