Species: Rhizocarpon richardii
Photos: On acidic coastal rock. Dunmanus Bay, Cork, SW Ireland.
Identified by Mike Simms
Brown to greyish-brown, areolate-cracked thallus, often with purplish tinge. Fimbriate blackish-brown prothallus is often present. Innate, flattish black apothecia with thin margins. The epithecium is dark-green or grey and K-.
Usually coastal, occuring on siliceous pebbles and rocks.
Medulla: K+/- yellow, usually C+ red, P+/- orange.
(R. hochstetteri and R. reductum are C-)
Rhizocarpon richardii on acidic coastal rock. March 2009