Caloplaca virescens. This really is the last photo I have of members of this genus. It has a pale to dark grey thallus, often tinged with blue, with fairly dark, rusty coloured fruits. It occurs on base rich bark of trees such as ash, sycamore etc. It is scarce, and has decreased due to Dutch Elm Disease. This photograph was taken on an ash tree at La Pedriza de Manzanares in the Sierra de Guadarrama, Spain