MYCOTAXON, cilt.105, ss.89-93, 2008 (SCI-Expanded)
Arthonia hawksworthii is described on the thallus of Dimelaena oreina from two localities in Turkey. It is most similar to A. gelidae, a lichenicolous species confined to Placopsis gelida, but mainly differs from this species in that it has ascospores with a gelatinous sheath that stain red in 1-Lugol and an epithecium that is light to dark brown with an olivaceous tinge in KOH. The new species is the first Arthonia species reported on Dimelaena.