Caloplaca ferruginea (Huds.) Th. Fr.
This is the corticolous counterpart of Caloplaca crenularia. It occurs on basic bark, and is relatively frequent in Western Scotland. It is characterised by a smooth, pale thallus with large bright-orange apothecia, which have uneven, flexose margins
Smith, C.W. et al. editors (2009) The Lichens of Great Britain and Ireland
Dobson, F.S. (2018) Lichens: an Illustrated Guide to the British and Irish Species
Schumm, F. & Aptroot, A. (2019) Images of the Lichen genus Caloplaca, Volume 2