Order: Lecanorales       Family: Rhizocarpaceae Species: Rhizocarpon lecanorinum Q Growth type crustose. Photos: On acidic upland rock. Ballingeary area, Cork, SW Ireland. Identification uncertain, needs confirming Bright-yellow or slightly greenish-yellow thallus with +/- crescent-shaped areoles surrounded by black prothallus. Areoles 1-2 mm diam., most often convex to rounded but sometimes flat. Black apothecia are approx 1mm diam with a thin, dirty green epithecium, K+ brighter green. Spores muriform, blackish brown with 15-38 cells, 34-57 x 15-24 µm Infrequent on metal-rich, upland siliceous rocks, walls and roofs. Medulla K+ yellow, C-, KC-, P+ brick red. Similar: Rhizocarpon geographicum

Rhizocarpon . Ballingeary area, Co. Cork. May 2009