Widespread and common in the British Isles, especially in the west and north. Primarily on siliceous rocks. The dark brown and dense areas of small isidia and largely saxicolous habit distinguishes it from Melanelixia glabratula

References: 
Thell & Moberg, editors (2011) Nordic Lichen Flora, Volume 4: Parmeliaceae
Dobson, F.S. (2018) Lichens: an Illustrated Guide to the British and Irish Species