A new isidiate saxicolous species ofPorina(Ascomycota,Ostropales,Porinaceae)

Porina collinaOrange, Palice & Klepsland is described as new from siliceous rocks in the Czech Republic, Great Britain and Norway. The thallus produces isidioid propagules which resemble those inP. rosei,P. hibernicaandP. pseudohibernica, but which are more fragile and poorly-defined, and almost ecorticate; the perithecial wall is dark purplish brown and the ascospores are 3-septate. Sequences of the mitochondrial ribosomal DNA suggest that the new species belongs in thePorina byssophilaclade.