Opegrapha dolomitica  

Thallus thin, often ± immersed and inapparent, smooth or finely cracked, creamy white, grey, greenish to brown-red.
Anamorph: conidiomata pycnidia. Conidia 4-6 × 0.5-0.7 μm, bacilliform.
Teleomorph: ascomata apothecia, lirellate, 500-1800 (-3000) x 150-250 (-350) µm, sessile to semi-immersed, scattered, infrequently
furcate, sometimes elliptical and gnarled, sub-gyrose or longitudinally furrowed. Disc persistently slit-like; exciple K–; epithecium brown, K–; hymenium 90-120 μm tall. Ascospores (20-)22-26(-31) × 5-8 μm, clavate, 3-septate (rarely 4-septate), usually with a thin perispore.
Chemistry: thallus C–, K–, KC–, Pd–, UV– (no lichen products detected by TLC).