Order: Lecanorales       Family: Porpidiaceae Species: Porpidia crustulata Growth type crustose. Photos: Gougane Barra, Cork, SW Ireland. Identified by John Douglass Very thin cream or pale-grey thallus that is sometimes only visible as a dark stain and can be reddish near water. The abundant black, convex apothecia (approx 1mm diam) are usually in lines or groups. Asci 8-spored. Spores colourless, simple, 10-16 x 6-9 µm. Porpidia soredizodes is probably the sorediate counterpart. Medulla usually K+ yellow, C-, P+ orange Common on siliceous rocks, stones, pebbles and upland scree. Similar: Porpidia cinereoatra

Immediately above: Porpidia crustulata, the Burren, April 2009