Trapeliopsis granulosa (Hoffm.) Lumbsch

    Thallus granular, composed of crowded granular to verrucose areoles, to 0.1-0.5 mm diam., pale grey, pale grey-greenish, sections sometimes pink when dry, morenpale grey-greenish when moist, spiked with minute soralia, 0.05-0.1 mm tall, and containing pale yellow-greenish soredia. N.B. Occasionally, when moist, some sections of the thallus become covered with a light brown jelly (never orange). Apothecia more or less frequent, usually rare or absent for highly sorediate specimen, 0.3-1.5 mm diam., disc flat then convex, sometimes tuberculate, brown-pink, brown-red, grey-blackish, exciple paler, thin, soon excluded. Ascospores ellipsoid, simple (a few becoming 1-septate), 9-14 x 4-6 µm. Photobiont: Chlorococcoid. C+ red-orage, red, K-, KC+ red, Pd-. Rather common but inconspicuous and consequently often understated. Grows on acid grounds at the base of stones and rocks, in heathlands. Rather frequent in areas subjected to seaspray in association with Pycnothelia papillaria.

See Trapeliopsis pseudogranulosa that is not fertile, with a more minutetely granular thallus and orange patches and thrives on humid plant debris. On decomposing wood, see Trapeliopsis flexuosa of which the thallus is verdigris.

N.B. Some specimen markedly granular (presented here) can present the appearance of Lepra (Pertusaria) amara soil form and especially Lepra (Pertusaria) amara Cf. forme du sol C+ orange but without the bitter taste and without KC + purple reaction! This is probably a particular taxon which deserves special study.