Erioderma pedicellatum (Hue) P.M. Jørg is a globally rare, foliose cyanolichen known from Scandinavia and southeastern Canada. In August 2007, several thalli of E. pedicellatum were collected in Denali National Park and Preserve on the south side of the Alaska Range, Alaska, USA. Subsequently, several additional thalli were observed in nearby Denali State Park. Together they represent the first report of E. pedicellatum within the United States and western North America and mark a major range extension for one of the most rare and endangered lichens in the world. The existence of a third global population center raises intriguing questions about the nature of the genetic relationships among eastern North American, western North American and Scandinavian populations.