Two new species ofArthoniaceaefrom old-growth European forests,Arthonia thorianaandInoderma sorediatum, and a new genus forSchismatomma niveum

Abstract

AbstractTwo new species ofArthoniaceaeare described from old-growth European forests:Arthonia thorianafrom Horner Combe in Great Britain andInoderma sorediatumfrom the Białowieża Forest in Poland. Phylogenetic analyses using mtSSU sequences were used to determine the generic affiliation of the two species.Arthonia thorianais characterized by a non-lichenized white thallus, pallid brown, white pruinose ascomata of 0·12–0·30 mm diam., richly anastomosing paraphysoids and (1–2–)3-septate ascospores of 9–12×3·0–3·5 µm.Inoderma sorediatumdiffers from all other species of the genus by a sorediate thallus and the production of confluentic acid. It is the sister species toI. afromontanumin our phylogenetic analyses. The discovery of the new species supports the high value of these forests for biodiversity action plans. Phylogenetic analyses also placeSchismatomma niveumin theArthoniaceaeand the new genusSnippociais described to accommodate it. The genusLepranthais resurrected for its type species (L. cinereopruinosa). A lectotype is designated forArthonia pruinosella.