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 et al. editors (2009) The Lichens of Great Britain and Ireland
Dobson (2018) Lichens: an Illustrated Guide to the British and Irish Species