Rinodina beccariana Bagl.
Rinodina subglaucescens (Nyl.) Sheard
Thallus crustose, 5-10 (20) cm across, thin to thick, sometimes roughly granular and irregularly cracked, dull withish, pale grey-glaucous, sometimes tinged with green, seldom with a well-developed black prothallus. Apothecia usually numerous, 0.7-1.25 mm diam., sessile or immersed in the thallus, disc continuously flat, black, blackish, exciple erect, 0.1-0.2 mm tall, persistent, crenulate, concolourous to the thallus or paler. Ascii clavate, 60-80 x 15-30 µm according to our measures. Ascospores broadly ellipsoid with thick walls, colourless or greyish, 1-septate (septum rather indistinct and hardly visible in water), locules spherical, 16-23 x 9-14 µm. Photobiont: Trebouxia. Thallus: C-, K+/- yellow, Pd-. Srong maritime trends, in shaded locations on protected siliceous rocks. N.B. Not to be confused with Rinodina confragosa that is Pd+ yellow, and with Lecanora gangaleoides that has simple ascospores. Specimen developing on ground, close to or on dying roots of Armeria maritima may be analysed considering the description of Rinodina roboris var. armeriicola.