Published online by Cambridge University Press: 29 July 2020
Porina collina Orange, 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 in P. rosei, P. hibernica and P. 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 the Porina byssophila clade.