Lecanora rupicola (L.) Zahlbr. subsp. sulphurata (Ach.) Leuckert & Poelt

    Thallus crustose, rather thick, tightly attached to the substratum, more or less cracked, areolated, smooth, pale green-yellowish when moist, yellow-glaucous to pale grey-yellowish when dry (yellow tinge is always observed), prothallus absent unless forming mosaics with other crustose lichens and then slightly bulging, black. Apothecia scattered all over the thallus, immersed, hardly protruding, 1-2 mm diam., disc flat, ochre, greyish, pale grey pruinose, exciple paler or inconspicuous (parasitized apothecia are common and turn blackish before destruction, leaving small rounded cavities). Ascospores ellipsoid, simple, colourless, 11-14 x 6-7 µm. Photobiont: green algae. C- or C+/- yellow, KC+ orange, Pd+/- yellow. Rare, oceanic and Mediterranean trends.*