Bacidia biatorina (Körb.) Vaïn.
Bacidia endoleuca auct. brit. pp.
Thallus crustose, to 2-4 cm long, rather thin, slightly granular, grey-greenish, greenish, occasionnaly with brown-orange to brownish spots. Apothecia rather numerous, distributed all over the thallus, 0.5-1.5 mm diam., flat, thick concolourous margin at first, later excluded, brown-red then blackish. Ascospores acicular, 10-15-septate, 60-80 x 3-4 µm. Pycnidia orange, in small number. Photobiont: chlorophycean. Chemical spot tests negative. Rare, oceanic tendency growing on bark of deciduous trees (Quercus). N.B. Bacidia laurocerasi differs by its whiter thallus and shorter ascospores. N.B. Bacidia caesiovirens is a close species that displays a blue-green thallus and seems to be distributed northbound.*