Tylophoron hibernicum (D. Hawksw., Coppins & P. James) Ertz, Diederich, Bungartz & Tibell

    Thallus crustose, thin, fibrous to powdery, white-pink at first, then dull white, white-greyish, sometimes white-greenish due to photobiont, margin darker, fimbriate. Overall surface covered with numerous sub-spherical sporodochia, 0.3-1 mm diam., pale white-yellowish. Photobiont: Trentepohlia. Thallus : C+/- red fleeting, K-, KC+/- red fleeting, Pd-; sporodochia : C+  bright red. Rare oceanic species, grows on bark of old trees (Quercus, seldom Ilex), most often at the base of trunks in dry places protected from seepage and direct rain. N.B. At first, this species is a parasitic lichen of corticolous lichens like Enterographa crassa, Schismatomma sp., Lecanactis abietina, Cresponea premnea, etc., then after capture of the host's photobiont (Trentepohlia), it can stand alone. Not to be confused with Lecanactis abietina, sterile and devoid of fully developed apothecia, that is rather similar, but has cylindrical pycnidia and not sporodochia and with pycnidia pruina C+ red (recollect that Tylophoron hibernicum may be its parasite and consequently both species may be found together). See also Enterographa brezhonega of which the chemical spot tests are negative.*