Thallus: crustose, verrucose to subsquamulose, slightly effigurate at the margins, bullate, ecorticate; prothallus: not visible surface: yellowish white to yellowish gray, glossy, epruinose, with an indistinct margin, esorediate Apothecia: immersed when immature, becoming sessile to slightly constricted at the base, 0.4-1.2 mm in diam., lecanorine disc: pale to dark red-brown, epruinose margin: concolorous with the thallus, thin, entire, ±verrucose to crenulate, without a parathecial ring amphithecium: present, with numerous algal cells, with large crystals insoluble in K, corticate; cortex: hyaline, ±gelatinous, inspersed, 15-25 µm thick laterally and 20-30 µm thick basally parathecium: hyaline, without or with very few small crystals, 10-15 µm thick epihymenium: reddish brown, K-, with numerous small crystals soluble in K, 10-15 µm thick hymenium: hyaline, clear., inspersed with oil droplets; paraphyses: sparingly branched and thickened apically; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid to subglobose, (3.5-)8-13 x 5-8(-13.5) µm Pycnidia: not seen Spot test: thallus and apothecial margin K+ yellow, C-, KC-, P+ pale orange Secondary metabolites: atranorin (major) and chloroatranorin (minor). Substrate and ecology: on exposed siliceous rocks at lowland elevation World distribution: subcosmopolitan, known from Africa, Australasia, North and South America Sonoran distribution: Baja California Sur and Sonora. Notes: Lecanora galactiniza can be recognized by relatively small apothecia, a well developed, subsquamulose thallus and a granulose epihymenium. Similar species include L. subimmergens and L. pseudistera. These are, however, distinguished by an egranulose epihymenium and a different chemistry. In addition, the thallus of L. pseudistera is usually much more robust than the thallus of L. galactiniza. This is the first record of this species for North America.