Description: This is virtually identical to Phlyctis argena (described elsewhere) but lacks the tiny, scattered surface soredia of that species. It has pale pink discs hidden by powdery warts resembling soralia (soredia-producing structures) that appear on the surface of the thallus like tiny white craters. These may be single, or multiple. It is a relatively frequent species in Ireland where it occurs most often on young, smooth-barked tree species, especially ash and sycamore.

Key Identification Features:

• The non-sorediate, disc-bearing, chalky-white thallus reacting K+ yellow to red strongly indicates this species
• Pertusaria multipuncta can look similar but is a generally larger crustose species with more exposed crater-like discs. It is however K+ yellow to brown only. The rare Pertusaria velata is C+ carmine red.

Original text submitted by Simon Davey

Distribution Map from NBN: Phlyctis agelaea at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Phlyctis agelaea at iNaturalist World Species Observations database.