Gyrographa saxigena (Taylor) Ertz & Tehler = Opegrapha conferta Anzi

    Thallus crustose, indistinct and inconspicuous, because very thin and evanescent, greyish, grey, grey-brownish or reduced to a simple greying of the substrate, very often absent and in this case this species is reduced to apothecia placed in fissures or around rock crystals. Apothecia lirelliform very prominent and as if they were just put on the substrate, isolated at first then in small compact piles or in a star shape on subsrates more or less smooth or even in series forming networks in fissures of the substrate, thin cracks well visible, bright, black. 8-spored asci, cylindrical to clavate with an ocular chamber, 65-75 x 15-18 µm according to our measurements. Club-shaped spores, 3-septate with more or less rectangular locules, 15-20 x 4-6 µm according to the literature, 16-20 x 5-6 according to our measurements. C-, K-, KC-, Pd-. A species with maritime tendencies that grows on rocks near the sea shore, acidic or weakly acidic, humid and in the shade, sometimes in cracks and fissures or around large crystals.

N.B. Taxon with very complex (and often invalid!) synonymy which has been variously interpreted, formerly treated in the Arthonia (Opegrapha) calcarea group as a separate species, either as a form or a variety.