Lecanora argentata (Ach.) Malme
On bark of deciduous trees and probably common in the west. The apothecial discs of L. chlarotera are usually rather more pale in colour than the other members of the Lecanora subfusca group which grow on bark and are superficially similar. The accurate determination of L. argentata usually requires microscopical investigation.
Smith, C.W. et al. editors (2009) The Lichens of Great Britain and Irelandd
Dobson, F.S. (2018) Lichens: an Illustrated Guide to the British and Irish Species