Irish lichens

Rhizocarpon lecanorinum

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

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