Melanelixia glabratula (Lamy) Sandler & Arup

    Thallus foliose, closely appressed to the substratum, 2-8 cm diam., lobes 2-5 mm wide, apices wavy to crenulate, upper surface glossy, green when moist, brown-green when dry, tinged reddish, covered towards the center with more or less numerous (but not forming a dense matt) cylindrical isidia, simple or coralloid, leaving a white scar when falling, soredia absent, lower surface  with simple rhizines, blackish towards the center, margin brownish. Apothecia rare, sessile, 3-5 mm diam., disc flat, sometimes concave, brown-red, pale brown, exciple more or less isidiate. Ascospores colourless, simple, ellipsoid, 10-14 x 5-8 µm. Photobiont: trebouxioid; cortex : K-, C- or C+ red in eroded sections, medulla: C+ red, KC+ red, K+/- purple-violaceous, Pd-. Rather rare species occuring on the smooth bark of the trunks of deciduous trees. See Melanelixia glabratula forme des rochers for the taxa coming on the siliceous rocks and which are of darker and intermediate colorations with Melanelixia fuliginosa and also Melanelixia glabratula forme des épaves en bois, lush form of this particular habitat (wooden wreck). Cf. Melanelixia subaurifera which has globular isidia and is soredial and Melanohalea elegantula with negative colored chemical reactions and Melanelixia fuliginosa which is much more covered with isidia which gives it a very dark blackish to blackish "wool carpet" appearance .