Thallus usually immersed and inconspicuous, more rarely areolate, pale grey, surface smooth to finely granular.
Anamorph: conidiomata pycnidia. Conidia 11-15 × ca 0.5 μm.
Teleomorph: ascomata apothecia, (0.1-) 0.2-0.6 (-0.9) mm diam., constricted at the base, slightly raised, often in small groups and
then becoming angular by compression. Thalline exciple well-developed, persistent, white, regularly deeply crenate with 5-8 segments, rarely not crenate. Discs rather variable in colour, red-brown to yellow- or brown-black, grey or blue-grey pruinose. Epithecium brown or blue, often interspersed with fine granules (N+ faintly pink, not dissolving in K). Hymenium 55-70 μm tall, yellow-brown above. Interascal tissue of paraphyses ca 2 μm diam., sparsely branched, the apices capitate, the terminal cell brown and swollen to about 3 μm diam. Ascospores 6-10 (-15.5) × (4-) 4.5-6 (-7) μm.
Chemistry: thallus C–, K–, Pd–, UV– (no lichen substances detected by TLC).
Assessed by Woods & Coppins as of Least Concern. This is a widespread species with a reasonably broad ecological amplitude.
Widespread, but more common in the south and east. BLS map here.
On hard calcareous rocks, walls and mortar.