Phlyctis agelaea (Ach.) Flot. Old & dry.
Thallus crustose, to 5-12 cm across, more or less cracked or verrucose, white-greyish, whitish, without soralia, prothallus white, delimiting. Apothecia deeply immersed, clustered by 2 to 4 at the center of flattened warts, irregular, powdery or granular, 0.2-0.5 mm diam., disc brown greyish, reddish, inconspicuous owing to dense pruine. Ascii 2-spored. Ascospores muriform, broadly ellipsoid, apiculate, colourless then brownish, 45-80 x12-30 µm. C-, K+ yellow > red, KC + red, Pd+ orange, UV-. Rare, on more or less smooth barks of trees (except resinous) in sheltered and weakly lit areas. See Pertusaria multipuncta which is K+ yellow.*