Family: Ramalinaceae
Lecania cyrtella (Ach.) Th. Fr.
Type: Crustose
Widespread and common on the bark of deciduous trees, biased towards Sambuscus and Fraxinus.
References:
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