Order: Lecanorales Family: Physciaceae
Species: Buellia stellulataGrowth type crustose.
Photos: On rock. Gougane Barra, Cork, SW Ireland.
Left identified by John Douglass
Small white to pale grey cracked thallus with a black prothallus, often forming mosaics. Immersed apothecia. Asci are 8-spored, spores brown, 1-septate, 8-15 x 5-8 Ám. Micro photo below.
K+ persistent yellow, C-, P+/- yellow, UV-
Usually coastal on hard siliceous rocks and pebbles.
Similar: Buellia aethalea. Greyer thallus, K+ yellow going red. Spores 13-18 x 6-12 Ám.