Biswamoyopterus gaoligongensis, a flying squirrel.
Photo: Kadoorie Farm & Botanic Garden

A newly described species of flying squirrel is teaching researchers more about these enigmatic, tree-hopping rodents, but its threatened status means scientists will have to act fast.

New research published today in ZooKeys describes Biswamoyopterus gaoligongensis, otherwise known as the Mount Gaoligong flying squirrel. Spotted in Yunnan Province, Southwest China, it’s one of only three known species of flying squirrel that belong to the genus Biswamoyopterus, the other two being the Namdapha flying squirrel and the Laotian giant flying squirrel.

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These nocturnal Asian animals are exceptionally rare. Scientists only became aware of this genus in 1981 after the discovery of a lone Namdapha specimen in Namdapha National Park, a large protected area in India’s Eastern Himalaya. The Laotian giant flying squirrel, a Red List threatened species, was discovered in 2013 in the form of bush meat being sold at a local food market in the Laotian province of Bolikhamxai. Both flying squirrels were considered large, at between 3 and 4 pounds (1.4 to 1.8 kg), but they featured physical differences that justified the creation of two distinct species.

The habitat of the newly described Mount Gaoligong flying squirrel.
Image: Kadoorie Farm & Botanic Garden

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Up until this new discovery, these were the only two specimens of Biswamoyopterus known to scientists. Strangely, however, their homes were separated by 776 miles (1,250 kilometers) in southern Asia. Why the two closely related species should be separated by such a vast distance remained a scientific mystery.

In a recent stroke of luck, a specimen belonging to Biswamoyopterus was unexpectedly uncovered in 2018 in the collections at the Chinese Academy of Sciences’s Kunming Institute of Zoology (KIZ). The scientist who made the discovery, Quan Li, traced the origin of the specimen to Mount Gaoligong in China’s Yunnan Province. At first, the investigators thought they were dealing with another Namdapha flying squirrel, but closer inspection suggested it was something else. The creature was definitely Biswamoyopterus, but differences in its color, skull, and teeth pointed to a new species.

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Image: Kadoorie Farm & Botanic Garden

This prompted a field expedition to Mount Gaoligong involving researchers from the Chinese Academy of Sciences, Kadoorie Conservation China, the University of New South Wales, and other institutions. This resulted in the discovery of another matching specimen, and field observations of two living flying squirrels.

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Like the KIZ sample, these squirrels featured a distinctive dark brown color (including a dark brown scrotum that contrasted heavily against its yellowish-white underbelly), bi-colored ear tufts, a short and wide skull, and uniquely shaped teeth. Together, these differences warranted the creation of the third known species of Biswamoyopterus.

The discovery was also important in terms of the geography involved.

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

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Image: Kadoorie Farm & Botanic Garden

Not much else is known about the new species, and a genetic analysis has not yet been conducted. Like other members of its genus, however, it’s nocturnal, prefing low-altitude forests and habitats near rivers.

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The Mount Gaoligong flying squirrels were seen close to nearby settlements, which is not great. Human activities could threaten an already sparsely populated species.

“Therefore, there is an urgent need to study the ecology, distribution, and conservation status of this rare and very beautiful genus,” said Quan.

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