Order: Arthoniales Family: Arthoniaceae
Species: Arthonia vinosa
Photos: Glengarriff woods, Co. Cork, SW Ireland.
Identified by Andy Acton
Thallus immersed or slightly powdery, whitish to yellow-orange, often with darker yellow-orange patches. Convex orange to dark brown apothecia to 0.5mm diam, +/- rounded, not pruinose.
Spores usually 1-septate, 10-15 x 4.5 Ám. Pycnidia are frequent.
Apothecia and darker patches on the thallus K+ purple.
Only occurs in old woods and parklands on the bark of old, rough-barked trees. Usually found on Oak, also recorded from Alder.
Similar: Arthonia spadicea. Spores smaller, 7-10 x 3-4 Ám.
Arthonia vinosa April 2010