Thallus: crustose, continuous or rimose-areolate; prothallus: not visible areoles: flat, thin or thick, opaque, ecorticate surface: smooth or rough, yellowish white to yellowish gray or yellowish brown or white to cream-colored, epruinose, with an indistinct margin, esorediate Apothecia: subimmersed or subimmersed when young, sessile when mature, 0.4-1.2 mm in diam., lecanorine disc: red-brown or orange-brown, plane, epruinose or slightly pruinose whitish gray margin: concolorous with thallus, thin or thick, persistent, even, not flexuose, smooth, entire, without a parathecial ring amphithecium: present, with numerous algal cells, with large crystals insoluble in K, corticate; cortex: distinct, basally thickened, gelatinous or interspersed, hyaline, 10-15 µm thick laterally, 20-25 µm thick basally parathecium: hyaline, containing crystals soluble in K epihymenium: red-brown to orange-brown, with pigment dissolving in K, with small crystals dissolving in K hymenium: hyaline, clear; paraphyses: not pigmented or red-brown to orange-brown, slightly thickened (up to 3 µm wide) apically; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid or narrowly ellipsoid, (10-)11-13.5(-14) x (5.5-)6.5-7.5(-8) µm wide; wall: less than 1 µm thick Pycnidia: immersed, cerebriform; conidiophores: type II sensu Vobis conidia: filiform, (14-)16.5-19(-20) µm long Spot test: thallus and apothecial margin K+ yellow, C-, KC-, P+ yellow Secondary metabolites: containing atranorin (major), chloroatranorin (minor), chlorolecideoidin (minor), gangaleoidin (major), leoidin (minor) and norgangaleoidin (trace). Substrate and ecology: on exposed siliceous rocks World distribution: a pantropical species, common in the dry tropics and on coastal rocks Sonoran distribution: Baja California Sur, Sonora and Sinaloa. Notes: Lecanora sulfurescens is a distinct species wih its red-brown to orange-brown apothecial disc and the presence of gangaleoidin. L. gangaloides also contains the gangaleoidin chemosyndrome, but is readily distinguished, since it has black apothecial discs. Morphlogically similar are some morphotypes of L. plumosa that can be separated by a different chemistry and an epihymenium with coarse crystals, while L. sulfurescens has fine crystals.