Picture taken on the 4th June 2007 close to Riu, Baixa Cerdanya, Oriental Pyrenees, Catalonia, on calcareous rock, vertical position, Nord oriented, temporary damp place, 1.400 m. altitude.
Lichen saxicolous, heliophilous, always on calcareous substratum, very common at Catalonia and in Europe.
Crustose thallus, dark brown to black areolate, coralliform surface in polaces, big, up to 10 cm, margin with no lobes but with a very evident felted prothallus with a beautiful blue colour.
Placynthium pluriseptatum is very similar, but with larger spores and more septate (up to 4 septa). Both lichens appear at the Pyrenees, for exemple at Nuria:
P. Navarro-Rosinés, N. Hladun , Flora liquénica de las rocas carbonatadas del Valle de Núria .