Arctoparmelia collatolica (Parmeliaceae), a new species from Siberia, Russia

Arctoparmelia collatolica is described as a species new to science based on morphological, chemical and molecular data. The species is similar to the usnic acid-deficient chemotype of A. centrifuga but differs in the grey-brown to brown upper surface in the central part of the thallus and ivory white to pale brown rhizines. The species contains collatolic acid and its derivatives. Seven secondary lichen substances are reported as new for the genus Arctoparmelia. A key to Arctoparmelia taxa is provided.