Species: Lecidea fuscoatra
Photos: On acidic rocks in the Burren and Co. Cork, Ireland.
Image below: On granite boulder. Black Head, the Burren. BLS meeting 2009
Cracked red-brown to greyish areoles surrounded by black prothallus. Immersed black apothecia are often white pruinose, sometimes convex with persistent margin.
Common on nutrient-rich siliceous rocks, also on old brick walls.
Upper cortex only: C+ red
Immediately above: Lecidea fuscoatra. Gougane Barra, August 2009. Identified by John Douglass