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(Map updated: 11 August 2009)

This is a lichen of coastal, siliceous rock cliff crevices where it is tolerant of some nutrient enrichment. At inland sites, the undersides of sheltered rock overhangs are favoured. The thallus is greyish-brown to black, sometimes with a tinge of mauve. The closely aggregated discs – slightly raised in shaded situations – have a thick rim (exciple). All reactions are negative. Spores are on the large side (to 23µm long). In Ireland, the species is known from a few localities, for example, the Glenderlough mica-schist, County Wicklow.

Key characteristics

• Thallus without soredia or isidia; grey-brown to black with a mauve tinge; discs crowded
• Coastal siliceous rock crevices and inland schistose cliffs; spores17–23µm long.

Original text submitted by Vince J. Giavarini