Order: Lecanorales       Family: Porpidiaceae Species: Porpidia macrocarpa Growth type crustose. Identified by Mike Simms (photos) Photos: On acidic coastal rock. Dunmanus Bay, Cork, SW Ireland. Very variable. Thallus usually immersed to thin and continuous, occasionally thicker and areolate. Usually pale greenish-grey but becomes reddish when oxidised. Prothallus indistinct when thallus immersed, but black, +/- visible when superficial. Large (to 3mm) abundant, shiny or matt, black apothecia with persistent margins, rarely pruinose. Epithecium pale brown to olive-brown. Common on siliceous rock, most frequent in upland areas. Medulla and apothecia margin: K+/- yellow, P+/- orange

Porpidia macrocarpa on coastal rock. March 2009