Lecanora pulicaris (Pers.) Ach. chémo P+

    Thallus crustose, smooth to minutely rough, seldom verrucose, pale greyish, pale grey-greenish, whitish when shaded, prothallus dark grey or absent, thallus surface seldom but possibly covered with scattered soralia, pale grey-greenish, 0.1-0.2 mm diam.,. Apothecia sessile, 0.5-1.5 mm diam., disc brownish, dark brown-red, dark chocolate-brown when dry or in herbarium, exciple determinate, smooth to rough, whitish. Ascopores simple, broadly ellisoid, 11-15 x 7-10 µm. Photobiont: Trebouxia. C-, K+ yellow, KC+ yallow, Pd+ red-orange  (seldom Pd-). Not especoially maritime, on tree barks, on ecorticate trunks, worked woods under decay. See Lecanora chlarotera which is Pd- and Lecanora argentata which is Pd+ pale yellow.*