Gyrophthorus perforans, previously known as a parasite on Umbilicaria vellea and U. hirsuta in Spain and Italy, is reported from Washington state in the Columbia River Gorge, where it was found infesting Umbilicaria phaea. The blistering infections make the host thallus resemble Umbilicaria subg. Lasallia. Historical records of Lasallia from the Pacific Northwest were checked for Gyrophthorus and found to be misidentifications of other Umbilicaria species, but additional records of Gyrophthorus were not found. Lasallia pensylvanica is confirmed from Alaska and British Columbia along with a single historic location in California, but has not yet been found in Oregon or Washington. Western North American Umbilicaria specimens with blistered surfaces should be checked for the parasite Gyrophthorus before assuming they belong to Umbilicaria subg. Lasallia.