Life habit: lichenized Thallus: crustose or squamulose, usually composed of contiguous to scattered areoles, sometimes rimose; prothallus: sometimes present areoles: angular to roundish in outline or irregularly shaped surface: white, gray, brownish yellow or brown, lacking secondary reproductive structures cortex: eucortex or phenocortex, often with a distinct epinecral layer medulla: white to spotted brown, I- photobiont: primary one a chlorococcoid green alga, secondary one absent Ascomata: apothecial, black or dark brown, immersed to sessile, lacking a thalline margin exciple: composed of radially oriented hyphae up to 5-7 µm wide peripherally, pale green to brown at least peripherally, photobiont cells occasionally present internally hymenium: hyaline below, pale green (N+ red), olivaceous or brown (N-) above, I-; paraphyses: branched and anastomosing, with +clavate apices hypothecium: hyaline, to brownish yellow or bluish red asci: clavate, nearly Lecanora-type but with rather pale amyloid reaction in the tholus and relatively narrow axial non-amyloid body, 8-spored ascospores: hyaline, simple, rarely 1-septate (sometimes falsely appearing so), ellipsoid to usually oblong-ellipsoid, thin-walled Conidiomata: pycnidial, immersed in areoles conidia: hyaline, simple, curved, filiform, 15-28 µm long Secondary metabolites: orcinol depsides and depsidones, and ß-orcinol depsides and depsidones Geography: primarily boreal and montane regions of the Northern Hemisphere but extending to Baja California Substrate: usually on acidic rocks, rarely on wood. Notes: Miriquidica is characterized by asci with a weakly amyloid tholus, lacking an amyloid zone above the axial body and with only a thin outer amyloid wall layer. Its spores are non-septate; its conidia, filiform; and the occurrence of miriquidic acid is nearly constant. It is closely related to Protoparmelia (Vol. II), Bryonora and Psorinia (Vol. I), but none of them have miriquidic acid.