The genus Xanthoparmelia includes several subcrustose, squamulose, small foliose, and small subfruticose species, primarily in the Southern Hemisphere. Here, we report on the first small foliose species lacking usnic acid in the genus occurring in the Holarctic. The species has been previously known as Lecanora olivascens Nyl., but subsequent studies of the morphology, secondary chemistry, and molecular data of the nuITS rDNA indicate that this species instead belongs to Xanthoparmelia. Consequently, the new combination Xanthoparmelia olivascens (Nyl.) V.J. Rico and G. Amo is proposed, and an epitype is designated here. We discuss the unique presence of a subcrustose Xanthoparmelia species lacking cortical usnic acid in the Northern Hemisphere. This species fits phylogenetically into a clade that was previously only known from the Southern Hemisphere, and hence represents another example of N-S disjunction in lichenized fungi. Keywords: Parmeliaceae; lichens; evolution; taxonomy; biogeographic disjunction.