Thallus: crustose, rimose-areolate areoles: poorly delimited and irregular in outline, flat, ecorticate but sometimes with a loose unorganised alga-free layer of various hyphae surface: pale yellowish green, dull, esorediate Apothecia: rounded to slightly irregular in outline, single or densely crowded, sessile with a constricted base, 0.30.6(-0.9) mm in diam. disc: yellow-orange to slightly brown or olivaceous, flat to moderately convex, dull, white pruinose when wet margin: weakly prominent when young, excluded with age, same color or slightly lighter than disc, dull, without a parathecial ring amphithecium: absent parathecium: biatorine, laterally 55-65 µm, basally 50-60 µm wide, with an outer layer of orange-brown granules, internally hyaline, composed of radiating, moderately branched and anastomosing hyphae with lumina 0.7-1 µm wide but apically 1-2 µm wide, with greasy granules epihymenium: orange-brown, formed by granules and amorphous pigment, c. 10 µm thick hymenium: hyaline, 45-55 µm tall; paraphyses: hyaline, weakly branched and anastomosing, with 1 µm wide and apically 1-1.5 µm wide lumina; subhymenium: hyaline, 30-60 µm thick; hypothecium: hyaline, 70-100 µm thick asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, (9.5-)11.2-11.4(-13) x (5-)5.7-6.2(-7.5) µm Pycnidia: not observed Spot tests: thallus K-, C+ orange-red, KC+ orange, P- Secondary metabolites: not tested, due to small size of the sample. Substrate and ecology: on bark of Lysiloma sp. and an unidentified deciduous tree at around 1000 m World and Sonoran distribution: Baja California Sur. Notes: Lecanora brucei is very similar L. symmicta, but the latter species is distinguished from L. brucei by having considerably narrower ascospores and a thallus consisting often of coalescing, areoles of 0.10-0.15 mm in diam.