Description: Thallus crustose, episubstratic, rimose-areolate to areolate, yellowish green to pale grey-green, without a distinct prothallus. Areoles 0.2-3 mm wide, Cortex 20-30 μm thick, with a thin epinecral layer with dead cells and crystals, and a thicker paraplectenchymatous layer which is divided into 2 sub-layers: an upper, pale brownish yellow layer rich in small yellowish crystals and somehow larger colourless crystals partially soluble in N, totally soluble in K, and a lower, colourless layer devoid of, or poor in crystals; algal layer continuous; medulla of mostly anticlinally arranged hyphae Apothecia lecanorine, adnate to sessile and constricted at base, round to irregular, 0.4-1.5 mm across, with a brownish to yellow-brown, flat to more or less convex, often umbonate disc, and a thin, flexuose-crenulate thalline margin. Thalline exciple up to 100 µm thick, corticate, rich in algae, the outer layer of cortex with granules and crystals; epithecium colourless to pale reddish brown, with granular crystals dissolving in K; hymenium colourless to pale yellow; paraphyses sparingly branched and anastomosing, slightly thickened at apex; hypothecium pale yellowish brown. Asci 8-spored, clavate, Lecanora-type. Ascospores 1-celled, hyaline, broadly ellipsoid, 10-14.5 x 5-6.5 μm, thin-walled. Pycnidia immersed, with a pale yellow-brown ostiole, Conidia acicular to arcuate. Photobiont chlorococcoid. Spot tests: thallus K- or K+ pale yellow, C-, KC+ yellow, P-. Chemistry: usnic acid, zeorin.
Note: on siliceous or slightly calciferous rocks in upland areas, with optimum above treeline. The description follows the concept of Roux & al. (2022).
Source: Roux C., Bertrand M., Poumarat S., Uriac P. 2022. Quelques espèces nouvelles saxicoles – calcifuges de Lecanora du groupe polytropa (Ascomycota, Lecanoraceae) découvertes en France. Bull. Soc. linn. Provence, 73: 79-120.