Trapeliopsis flexuosa (Fr.) Coppins & P. James

    Thallus crustose, uneven and small granular areoles, 0.1-0.2 mm (up to 0.4 mm at margin), covered with sorelia, starting from a few at first then spreading, and with farinose soredia, grey-greenish tinged blue, dark blue greenish, typically verdigris. Apothecia rare and vague, 0.2-0.7 mm diam., disc flat or slightly convex, dark green, blackish when lit and pinkish when shaded, exciple paler but almost invisible. Ascospores ellipsoid, simple, 7-9.5 x 2.5-4 µm. Photobiont: chlorococcoid. Thallus : C+ red, K-, KC+ red, Pd-. Mostly on rotting wood, notably decaying lumbers (poles, fences, etc.) even stained or painted. See Trapeliopsis granulosa  of which the thallus is more granular and not verdigris, and grows mainly on plant debris.