ASCOMYCOTA | LECANOROMYCETES > PERTUSARIALES > Megasporaceae

Common name:             -

Synonyms:                      Aspicilia calcarea, Lecanora calcarea

Habitat:                          Coastal (for this entry), but also urban

Substrata:                     Rock, stone

Growth form:                Saxicolous

Thallus:                 Crustose

Apothecia:                    Lecanorine

BLS identity rating:        Graded 1/5 (identification should be straightforward)

Thallus typically forming roughly circular patches around 20-25cm dia., although sometimes larger, surface smooth, finely cracked-areolate, often becoming almost placodioid; chalk-white to pale grey, and often surrounded by a slightly darker thickened prothallus with radiating cracks; apothecia can be numerous, irregular in both size and shape, more or less immersed, discs concave, black, although white-blue-pruinose when fresh, thalline margin thickened, slightly raised when young, but then disappearing, one or more in the centre of each areole.

Common on hard limestone rocks, also on walls and tombstones, but not cement or mortar.