Description: This is a common crustose lichen of siliceous maritime rocks. It can form tremendous colonies with sea-ivory, Ramalina siliquosa (described elsewhere) along exposed sea cliffs. The finely cracked, white to grey thallus bordered by a black line, supports abundant black discs (to 1.5mm diam.) with a conspicuous white-frosted margin. Spores are one-septate. Spot tests: K+ yellow-red, Pd+ yellow. Throughout Ireland.

Key Identification Features:

• Very common with a white to grey thallus, black discs and frosted margin frequently in the sea-ivory zone
• Reacts K+ yellow-red, C-, Pd+ yellow.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Buellia subdisciformis at iNaturalist World Species Observations database.