Description: This is a species of upland siliceous rock, common and widespread like P. macrocarpa and P. crustulata, but differs from both of these in its much whiter thallus colour. Discs are numerous, black, sizeable (to 2mm diam.), sunk into little islands of cracked thallus, barely convex and mostly frosted over with grey pruina. Look for it on low outcrops, boulder, and drystone walls in the uplands.

Key Identification Features:

• The moderately large, often pruinose, rather flattened fruits on a white-grey areolate thallus growing on acid-natured rocks indicate this species
• Note: There may be forms of Porpidia material that are atypical and it is not always easy to assign it to species without carrying out specific laboratory chemistry.

Original text submitted by Simon Davey

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

iNaturalist: Porpidia cinereoatra at iNaturalist World Species Observations database.