Description: This species of Porpidia is best known by its thick, grey-white, crumbly thallus with soralia that form lines in the cracks across the surface. Discs are rare, black, clustered often with a veil of pruina, like sprinkled icing sugar; medulla I-. Damp rocks, for example, lough edges, sea cliffs; ranging from high uplands to sea level. Rare in Ireland.

Key Identification Features:

• Thallus grey-white, crumbly with swellings, uneven; discs black, rare
• Soredia bursting onto the surface though cracks in the cortex; damp siliceous rock.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Porpidia rugosa at iNaturalist World Species Observations database.