A southern flying squirrel.
A southern flying squirrel. Ken Thomas/Public domain

Across the continent of North America, there is great north/south divide—for flying squirrels. Southern flying squirrels live in the eastern half of the continent, from southern Canada down to Florida, and in the highlands of Central America. Northern flying squirrels live across Canada and up into Alaska. The two population were long separated by glaciers. As National Geographic reports, the key difference between the two species is the morphology of their penis bones, but they’re not really all that different—there are even north-south hybrids in some places.

Until now, flying squirrels that live on the West Coast of the United States were grouped with the northern species. But Brian Arbogast, of University of North Carolina Wilmington, had a hunch that they might not be part of the same tribe.

“There was just something weird” about the West Coast squirrels, he told National Geographic. (East Coasters can understand the sentiment.) The West Coast squirrels didn’t look quite like the rest of the northern squirrels, and in a new paper published in the Journal of Mammalogy, Arbogast and his colleagues identify these West Coasters as a new species, named Humboldt’s flying squirrel, after the naturalist Alexander von Humboldt.

The report states that besides the physical differences (West Coast squirrels are “smaller and darker” than the northern squirrels, according to National Geographic) the Humboldt’s flying squirrels are genetically distinct. In fact, they are more different from northern flying squirrels than the northern and southern species are from each other.