Order: Lecanorales       Family: Rhizocarpaceae Species: Rhizocarpon lecanorinum Crescent map lichen Growth type crustose. Photos: On acidic upland rock. Ballingeary area, Cork, SW Ireland. Identification very uncertain, needs confirming or correcting Bright-yellow or slightly greenish-yellow thallus with +/- crescent-shaped areoles surrounded by black prothallus. Black apothecia are approx 1mm diam with epithecium pale green-brown, K-. Occurs on metal-rich, upland siliceous rocks, walls and roofs. Medulla K+ yellow, P+ orange Similar: R. geographicum

Rhizocarpon lecanorinum. Ballingeary area, Co. Cork. May 2009