Order: Pertusariales Family: Pertusariaceae
Photos: Macroom, Co. Cork and Killarney, Co. Kerry, SW Ireland.
Specimen left and immediately below confirmed by Brian Coppins
Thin grey-white to pale greenish-grey thallus containing clusters of coarse crystals. Margin +/- unzoned. Scattered flat-topped warts with spreading, +/- elliptical bases. Apothecia usually single with small pore-like discs. Pycnidia are rare. Asci (3-) 4 (-6) spored, the spores (40-)50-80(-120) x (20-)25-40(-50) Ám.
Microscope photographs below.
K+ yellow, C-, KC+ yellow, P+/- orange-red, UV+/- pale orange
Occurs throughout Ireland on sheltered, shaded, smooth-barked deciduous trees and shrubs.
Similar: Pertusaria pertusa, 2-spored asci