Ochrolechia tartarea  

Thallus often very thick, to 3 mm or more, ± white to dark grey, surface soft, often powdery-tartareous, often with numerous irregular warts forming an uneven, corrugate crust, sometimes with a paler zoned margin and a pale prothallus. Isidia and soredia absent. Photobiont chlorococcoid.
Anamorph: no information available.
Teleomorph: ascomata apothecia, usually frequent (sometimes absent), immersed and closed at first, becoming rounded or irregular, scattered or crowded, sessile. Thalline exciple thick, wavy. Disc to 5 (-8) mm diam., pale brown to dull orange-pink, concave to flat, not or translucently pruinose, the surface often scabrose-roughened. Epithecium granular, the granules dissolving in K. Interascal tissue of thin, densely branched and anastomosed paraphyses. Asci with thick amyloid walls, 8-spored. Ascospores (35-) 40-70 × 20-40 μm, broadly ellipsoidal, aseptate, thin-walled, smooth, without an epispore, gelatinous sheath or appendages.
Chemistry: thallus C+ orange-red, K+ pale yellow (sometimes hardly noticeable), KC+ red. Medulla Pd–, UV–. Apothecial disc C+ vermilion red, K–, KC+ red, Pd– (gyrophoric acid, lecanoric acids (trace)).