Thallus: foliose, umbilicate, small cushions or rosettes up to 20 mm wide, lobes 2-5 mm wide or long, erect or if not at least margins ascending, irregularly branched, broadly rounded surface: bluish-gray pruinose, partially also black, often with small, globose isidia, otherwise smooth Apothecia: not seen in Sonoran material, elsewhere rarely present, small, immersed to semi-immersed, zeorine; disc: slightly depressed, brownish, with persisting thalline margin; exciple: up to 10 µm wide, hyaline; hymenium: up to 150 µm high, hyaline, amyloid; paraphyses: distinctly septate, sparingly branched and anastomosing, apical cells slightly thickened up to 3 µm asci: 8-spored ascospores: simple, hyaline, globose to broadly ellipsoid, 7.5-10 x 5-7.5 µm; walls: thin Pycnidia: immersed, globose, up to 0.1 mm wide conidia: cylindrical, 3 x 1 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on limestone on shaded, steep or vertical rock faces in chaparral or woodlands World distribution: North America, Europe, Socotra Island, probably Asia and North Africa Sonoran distribution: limestone deposits in central Arizona and Baja California Sur. Notes: Older floras usually listed the species under the name Thyrea pulvinata auct., that may in fact represent Thyrea confusa but possibly also Lichinella iodopulchra (Henssen and Jørgensen 1990). Lichinella iodopulchra may also have pruinose lobes and deeply lobate thalli especially when old. However, it is distinguished by the absence of globose isidia, its usually down curved margins, its type of ascomata (thallinocarp), and the number of spores (>16). Also similar is Lichinella nigritella, which is usually deeply divided, with more slender and streched, erect lobules that are normaly not pruinose. The latter species also has larger globose to squamulose isidia; if it is fertile, then it is also distinguished by the type of ascomata (thallinocarp) and spore number (>16).