Thallus: crustose, effuse, areolate areoles: irregular in outline, 0.25-1.5 (-2) mm wide, 0.2-0.5 (-1) mm thick, surface: black, warty to granulose, uneven, rarely smooth lower surface: attached to the substrate by rhizohyphae Apothecia: semi-immersed to sessile, zeorine, 1-3 per areole, up to 0.4 mm wide; disc: at first punctiform and depressed, later open and ± flat, reddish brown, with persisting, thin thalline margin; exciple: 25-50 (-75) µm wide, thick only in mature apothecia, hyaline or yellowish brown in apical parts, often visible as a light ring when mature apothecia are moistened, in juvenile apothecia remnants of conidiophores often present between hymenium and exciple (former pycnidial wall); epihymenium: faintly reddish brown; hymenium 125-200 µm high, hyaline, amyloid; paraphyses: very thin, indistinctly septate, sparingly branched and anastomosing; apical cells: slightly thickened (-3 µm) asci: 8-spored ascospores: simple, hyaline, broadly ellipsoid to globose, (7.5-) 10-12.5 (-15) x (5-) 7.5-10 µm; walls: thin Pycnidia: immersed, globose to broadly pyriform, 0.075-0.125 mm long, 0.075-0.1 mm in diam. conidia: cylindrical, 3 x 1 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on siliceous (granite or volcanic) or calcareous rocks, sometimes mixed with mosses over weathered rocks, inclined or horizontal surfaces in shaded or sheltered rock faces of boulders; mainly montane World distribution: North America, Europe, North Africa Sonoran distribution: central and southern Arizona, southern California; Baja California Sur. Notes: Very similar are species of Psorotichia, which have a thinner (<15 µm) proper exciple, that may even lack and a subhymenium that usually extends as a stipe deeper into the thallus. Also similar is Lemmopsis arnoldiana whis apparently is confined to limestone or caliche and which shows a characteristic yellowish-golden coloration in the entire exciple. Unlike Porocyphus, in Psorotichia and Lemmopsis the ascomata arise from a tangle of generative hyphae and the paraphyses are more robust.