In the heart of Canada’s Rocky Mountains, an unassuming yet remarkable butterfly has been quietly flying under our scientific radar for years. With a wingspan of an inch to an inch and a half, and wings that are brown on top and grayish brown with black spots below, this population was long thought to belong to the Half-moon Hairstreak (Satyrium semiluna). However, the isolated hairstreak butterflies of Blakiston Fan in Waterton Lakes National Park, Alberta, have now been recognized as a distinct species: Satyrium curiosolus, or the Curiously Isolated Hairstreak.

A recent study by an international collaborative team, published in ZooKeys, uncovered the unique evolutionary history of this population. The results were striking: Satyrium curiosolus has been completely isolated from its closest relatives for quite a while—possibly up to 40,000 years—becoming more and more genetically and ecologically unique along the way.