Letharia gracilis (Parmeliaceae), a new species from California and Oregon

Letharia gracilis Kroken is validated as a new species of lichenized fungi from California and southern Oregon. Previously lumped under L. columbiana, but recognized as a distinct lineage by molecular work of Kroken and Taylor, L. gracilis is distinguished from L. columbiana by its sparse branching, slender, relatively smooth, drooping branches and distinct ITS DNA sequences.