Description: This powdery, crustose, epiphytic lichen is a recent addition to the Irish lichen flora. It is a species of the waysides, so is absent from woods. The pale grey thallus is finely cracked and tinged with yellow which gives it a distinctly lime green appearance and useful field character. The yellowing is a flush of powdery soredia which spreads thinly across the surface. The edges of the thallus are place to see the white prothallus growing out from below the crust. Discs are rare. Spot tests: K+ yellow-red, C-, PD+ yellow.

Key Identification Features:

• Thallus crustose, cracked, grey to lime green; wayside trees
• Soredia fine, powdery, yellow-green; K+ yellow-red, C- (NOTE: both Lecanora expallens and Pyrrhospora quernea are C+ orange).

Original text submitted by Vince J. Giavarini

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

iNaturalist: Lecanora barkmaniana at iNaturalist World Species Observations database.