Description: This tiny micro-lichen invades the surfaces of smooth, siliceous pebbles, shrubby stems and dry worked timber forming black speckles on a thin grey thallus overlying a lower stratum of dark grey prothallus. This gives it the appearance of a three-tone mosaic. The black speckles are the discs (average size = 0.2–0.4mm diam.) most of which remain flat. In a squash of the discs in K, prepare to see green, blue, and sometimes, reddish pigments. The spores are simple. In Ireland (where flinty rock is rare), the species is sparingly distributed throughout.

Key Identification Features:

• Minute flat, black discs on a grey thallus over a darker prothallus. Under the microscope: spores simple, floating among blue-green pigments
• On very small, smooth pebbles; also among gorse or heather in open situations.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Leimonis erratica at iNaturalist World Species Observations database.