Halecania ralfsii (Salwey) M. Mayrhofer
Thallus crustose, more or less effuse, 2-6 cm across, rimose, cracked, made of convex areoles organized as a 'macaronis dish', or like if tooth paste had been spread, surface striated or pleated or even graven, waxy textured, typically grey-blue to leaden-grey or slate-grey, bluish spotted with brown or green in eroded places. Apothecia usually rare, 0.2-0.5 mm diam., urn-shaped and prominent at first, then slightly laid on thallus, disc mostly flat at first then slightly convex, dark brown to black, paler when old, thalline margin concolorous with thallus, possibly vanishing with age. Pycnidia numerous visible as minute black dots. Ascospores broadly ellipsoid, 1-septate with one perispore (clearly visible and swollen in K), 15-17 x 6-9 µm. Photobiont: chlorococcoid. Thallus C-, K± yellow, Pd+ red. Rare in our prospection area and, in that case, localized (and potentially then abundant), on shaded siliceous rocks of the mesic zone. Often associated and possibly confused with Lecanora helicopis which is grey-bluish, Pd- and grows in more well-lit habitats. N.B. In some areas this species frequently is associated (parasite ?) with Verrucaria (Hydropunctaria) maura grp.