Flavoplaca oasis (A. Massal.) Arup, Fröden & Sochting morpho oasis = Caloplaca oasis (A. Massal.) Szat.

    Thallus crustose, rather thin, more or less immersed, possibly continuous or areolate but often discontinuous, forming areoles (0.1-1 mm) clusters, pale yellow, grey-yellowish, dull yellow, sometimes dark brown or blackish in nutrient-rich environments, prothallus and soredia absent. Apothecia numerous, usually clustured and sometimes crowded, 0.2-0.6 mm diam., disc plane when young and then slightly convex, brown-orange, dark orange when dry, orange-yellowish when moist, exciple thin usually persistent, concolourous or paler. Asci cylindrical, 8-spored. Ascospores polarilocular, ellipsoid, colourless, 9.5-13 x 4.5-6.5 µm, with a large septum up to 3-4 µm for mature ascospores (ratio septum/ascospore: 0,24-0,37). Apothecia K+ purple. Slightly thermophile species, on hard calcareous rocks, and seldom on mortar and concrete, see: voir Flavoplaca oasis eco lithophila,, and in that case hardly distinguishable from Caloplaca holocarpa ss. str. This species is usually parasitic of Verrucaria sp. at least at first, and shares a common habitat. Later they seem to be autonomous. See other parasitic species but Aspicilia: Caloplaca inconnexa and Caloplaca necator which are much more thermophilic.