Lecania erysibe (Ach.) Mudd

     Thallus crustose, highly variable, thin, granulose, areolate, areoles angular more or less regular, covered with blastidial granules composed of fungus hyphae, pale brownish, yellow-brownish, yellowish, olivaceous when dry, grey-greenish, brown-greenish when moist. Apothecia usually numerous, scattered or in small clusters, 0.2-0.6 mm diam., disc flat then slightly convex, brown-orange, grey-orange, brownish, dark brown, exciple thin with a granular aspect due to yellow-greenish blatidia. Ascospores ellipsoid, 1-septate, 10-15 x 3-5 µm. Photobiont: chlorococcoid. Chemical spot tests negative. Inconspicuous species, undertsated and neglected growing in dusty and dull areas, notably in cities and resistant to pollution, mostly on calcareous rocks, concrete, seldom on bark of ornamental trees in cities. N.B. This species is easy to confuse with Lecania inundata which can come nearby but which is distinguished by the presence of numerous nodules (much larger than the blastidia), gray-greenish turning green with humidity and its apothecia often grouped together and without a grainy margin.