Schismatomma quercicola  Coppins & P. James

    Thallus thin, smooth, minutely irregular or verrucose, pale grey, pale greyish, pale grey-greenish when moist, pale grey-brown when dry, sometimes with green patches owing to algae, soralia scattered all over the thallus, 0.2-0.5 mm diam., pale greyish when moist but whitish when dry, not contiguous. Apothecia unknown in our prospection area. Photobiont: Trentepohlia. K-, C-, KC-, Pd+ orange. Rare in our prospection area, on bark of deciduous trees, notably Quercus, either isolated or in humid and exposed woodlands. N.B. General aspect similar to Opegrapha vermicellifera but the latter has a more greyish thallus and white powdery pycnidia, Lecanactis subabietina has also pycnidia and a more greyish thallus, but is K+ yellow whereas  Tylophoron hibernicum  is C+ red and has large sporodochia. Watch out for Schismatomma niveum also P + orange but with confluent soralies.