Loxospora elatina (Ach.) A. Massal.

    Thallus crustose, 2-5 cm across, very thin, smooth or minutely verrucose, pale greyish, pale grey-greenish, covered with globose or tuberculate soralia, 1-2 mm diam., green-yellowish, green-bluish, very pale greenish, prothallus whitish, arachnidan. Apothecia very rare, 1-1.5 mm diam., disc brown-reddish, reddish, exciple thin and sorediate. Ascospores colourless, fusiform to narrowly ellipsoid and spiral-shaped in ascii, 3-5-septate, 35-50 x 4-5 µm. Photobiont: trebouxioid. Thallus and soralia: C-, K+ immediately yellow but vanishing, KC+ yellow, Pd+ yellow-orange, orange (slow reaction). On bark of trees, notably rough barks. N.B. Many species with similar aspect, belonging to different genera, cannot be distinguished unless chemical spot tests are carried out (see Lecanora expallens, C+ orange and Pd-; Pyrrhospora quernea,  C+ orange, etc.).*