Description: This lichenicolous species is easily told from its host Porpidia spp., and principally P. contraponenda. The whitish thallus supports abundant black discs (0.2-0.3mm diam.), some, but not all, with a central umbo. All spot test reactions are negative. In Ireland, the species is local; County Mayo northwards.

Key Identification Features:

• Whitish thallus developed on Porpidia species in upland areas
• Discs small, black, some with a central umbo; spot tests negative.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Cecidonia xenophana at iNaturalist World Species Observations database.