Thallus: crustose, thin, up to 0.6 mm thick, with a few thicker nodules or areoles, sometimes uniformly compacted, rarely crumbling into individual nodules; prothallus: absent areoles: scattered to grouped, mostly not angular, up to 2 mm wide surface: yellow-brown to gray-brown and dark brown, at times becoming greenish when wet (cortex then very clear and translucent), with concolorous edges, with small papillae, which are paler and more conspicuous when moist, dull to slightly shiny, epruinose cortex: often developed, up to c. 50 µm thick, with a phenocortex, partly intergrading into an epinecral layer medulla: not developed; algal layer: not clearly separated Apothecia: broadly to narrowly sessile, round, scattered to often clustered in small groups, rarely deformed, up to 0.8 mm in diam. disc: pale brown, orange-brown to dark brown, becoming translucent and dark-spotted when wet, flat to moderately convex, at times strongly convex when old, rarely white-pruinose margin: almost always present, pale gray to pale brown, in young apothecia almost swollen, c. 0.1 mm wide, slightly raised then level, later somewhat receding, often incompletely fissured amphithecium: with an algal-rich medulla and algal-free cortical zone particularly well developed towards the base of the apothecia, sometimes transformed into an epinecral layer parathecium: sometimes present in places or throughout, the outer cell walls of which may be concolorous with the epihymenium epihymenium: pale orange, red-brown to dark brown, rarely black-brown, spotted, the pigment often shows especially around the coherent paraphyses tips and extends deep into the hymenium; epipsamma partly richly present, slightly yellow or brown hymenium: hyaline below, 60-85 µm tall; paraphyses: 2.5-3 µm wide below, hardly or slightly swollen towards spices but at least some usually strongly swollen (to 5 µm wide), with the apical cell distinct, externally brown-pigmented, coherent due to epipsamma in a gelatinous matrix; hypothecium: hyaline to rarely pale yellow, the hyphae intricate to paraplectenchymatous below, up to 70 µm thick asci: +narrowly clavate, 8-spored, 55-60 x 10 µm ascospores: hyaline, (0-)1-septate, straight, not constricted, oblong-ellipsoid, 11-15(-18) x 4.5-5.5(-6) µm, thin-walled Pycnidia: rare, immersed, c. 100 µm in diam.; wall: pale, red brown near ostiole; ostiole: 60-80 µm deep; conidiogenous cells: branched at base, elongate, cylindrical, c. 2 µm in diam. conidia: filiform, strongly curved, 14-20 x 0.8 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: mainly on limestones, and calcareous rocks, rarely on acidic rocks, on artificial substrates such as mortar and brick of old walls, mostly in rather sheltered and somewhat shaded situations World distribution: widely distributed throughout Europe and North America Sonoran distribution: southern California (Channel Islands). Notes: Lecania inundata is characterized by its small papillae on the surface of the nodules and areoles. The individual papillae are larger than blastidia, have a smooth upper surface and well-developed, algal-free zone, that may in part be transformed into a layer of dead cells (M. Mayrhofer 1988). Somewhat similar species in the Sonoran region include L. fructigena, that differs by having a more papillate thallus, darker apothecia and a different ecology. Lecania brunonis has a verrucose-areolate-subsquamulose thallus without nodules or small papillae and a browner, shiny thallus. In Nash 32183, L. brunonis and L. inundata grow together on acidic rock, and the thallus of the latter is somewhat less developed. If not well developed, L. inundata can be overlooked for other species, such as L. rabenhorstii. Although the type collection was made on inundated granite blocks along the Neckar River,