Thallus thin, less than 150 (rarely 250) µm thick, grey to brown-black, (pale grey or white-pruinose in GB material, indistinctly areolate; areoles (150–) 200–450 (–600) µm diam. Prothallus present, dark grey. Marginal squamules and vegetative diaspores absent. Cortex absent; alveolate cortex (sensu Vondrák et al. 2009) present in spots (<20 µm thick).
Anamorph: Pycnidia common, usually observable as darker spots in thallus. Conidia ellipsoidal, ca 2.5–3.5 x 1.0–1.5 µm.
Teleomorph: Ascomata apothecial, <0.7 mm diam., biatorine, orange to red (grey in variants without anthraquinones), K+ purple, C+ purple, I– (disc I+ blue due to reaction with asci), P– (but red pigment dissolves in acetone solution of P), UV–; no visible spot reactions in grey apothecia. Exciple usually paler than the disc. Proper exciple c. 100–130 mm thick, prosoplectenchymatous. Thalline exciple ca 60–120 µm thick. Hymenium c. 90–110 mm high. Interascal tissue of paraphyses, branched and anastomosed, with tips widened to 3-6 µm. Asci clavate, c. 55–75 x 18–26 µm. Ascospores 13–16 (–17) x (7.0–) 8–10 (–11) µm; average ratio of ascospore length/breadth 1.7:1; septa (3.5–) 4.5–6.5 (–8.0) µm wide.
Specimens from Great Britain have a pale grey thallus with an indistinct amount of the grey pigment, in contrast to specimens from the Mediterranean regions which have a darker thallus, with an observable Sedifolia-grey content in sections.
GB&I: reported from Wales (Pembrokeshire). Common in the eastern Mediterranean and Black Sea regions
On siliceous cliffs, outcrops or stones not far from the sea coast.