Description: While natural limestone will attract this species it is often more plentiful on artificial substrata such as boundary wall tops, concrete posts and mortar where there is less competition from lime-loving lichens. The crusts may begin as grey-green speckled or granular stains which later become thicker and cracked. The 1mm-diam. discs which form as soon as the thallus has established resemble black fruit gums in miniature and occur either singly or in clusters. A useful microscope character (look at a squashed slice of the disc) is the lack of any strong pigmentation around the base of the disc (fruit). This helps to eliminate lookalike species such as Clauzadea monticola.

Key Identification Features:

• A grey-green speckled-granular stain with scattered fruit-gum-like discs
• Common on walls, mortar and artificial stonework with a low lime content often in the company of Caloplaca holocarpa, Candelariella vitellina, Lecanora campestris and Lecidella scabra.

Original text submitted by Vince J. Giavarini

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

iNaturalist: Lecidella stigmatea at iNaturalist World Species Observations database.