Order: Lecanorales       Family: Physciaceae Species: Buellia aethalea Growth type crustose. Photos: On acidic rock. Ballingeary area, Cork, SW Ireland. Thick or thin, mosaic-forming areolate thallus, often less than 2cm diameter with black prothallus. Areoles are pale to dark grey, sometimes tinged brownish. Abundant immersed apothecia with small black discs. Pycnidia are rare. The asci are 8-spored, spores brown, 1-septate, 13-18 x 6-12 µm. Chemical reactions variable. Sometimes negative, or K+/- yellow going red, C-, P+/- yellow-orange, UV- Acidic rocks, pebbles and dry stone walls, often pioneer species. Similar: Buellia stellulata, whitish thallus, K+ persistent yellow Buellia ocellata, greenish-yellow thallus, C+ orange, Placopyrenium fuscellum, chemical reactions negative.

Buellia aethalea. August 2009 and December 2008