Order: Arthoniales       Family: Roccellaceae Species: Opegrapha zonata Growth type crustose. Previously Enterographa zonata Photos: On shaded rock. Gougane Barra, Cork, Ireland. Identified by John Douglass Mosaic-forming cracked or smooth chocolate-brown thallus, often violet-tinged. Dark prothallus. Mauve-tinged dark-brown soredia on surface erode leaving paler patches. Apothecia rare. Occurs on damp, shaded siliceous rocks. Chemical reactions negative. Similar: Opegrapha gyrocarpa. Soralia C+ red.

Immediately above: Opegrapha zonata on granite erratic, the Burren, April 2009