Description: This tiny crustose lichen occurs among larger mosaic-forming species on exposed, hard siliceous rocks in upland areas. The dark brown convex discs arise from a grey-brown warty thallus. In a squash section, the discs are seen to be brown above and colourless below. In Ireland, the species has been recorded from north-west Donegal but should be searched for on the acid outcrops of the south and east.

Key Identification Features:

• Tiny, dark brown convex discs on exposed, hard siliceous rocks in the uplands
• A simple squash of the disc will reveal a brown ‘upper’ layer above a colourless zone; there are no bright pigments present; Scoliciosporum umbrinum is similar but has spirally twisted, three- to five-septate spores.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Micarea subnigrata at iNaturalist World Species Observations database.