Description: This species is rare in Ireland but is easily overlooked on account of its habitat of dry siliceous rock such as below the overhanging tops of granitic outcrops and boulders or the associated stony debris towards the rear of these gaping recesses. The buff to pale green thallus gives rise to tiny, blackish, convex discs that are frequently warted or ‘tuberculate’ containing the simple to one-septate spores that never broaden beyond 2.5µm (unlike in M. sylvicola a lookalike species, which widens to almost twice this size).

Key Identification Features:

• On dry siliceous rocks/boulders (especially on undersides levered up 50cm or more above the ground); discs small, black, warted
• Spores oblong (not ovoid as in M. sylvicola).

Original text submitted by Vince J. Giavarini

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

iNaturalist: Brianaria tuberculata at iNaturalist World Species Observations database.