Thallus: crustose, continuous or rimose-areolate; prothallus: not visible, or white areoles: flat, thin or thick, opaque or glossy, epruinose, ecorticate surface: yellowish white to yellowish gray or whitish gray to gray or gray to dark gray, smooth, with an indistinct margin, esorediate Apothecia: immersed, aspicilioid, 0.3-0.8 mm in diam. disc: red-brown or brown, plane, epruinose margin: concolorous with thallus, without a parathecial ring amphithecium: absent parathecium: hyaline, containing crystals soluble in K epihymenium: red-brown to orange-brown, with pigment not dissolving in K, without crystals hymenium: hyaline, clear; paraphyses: red-brown to orange-brown, capitate (up to 4 µm wide) apically; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, (8-)8.5-14.5(-15) x 4.5-5.5 µm; wall: less than 1 µm thick Pycnidia: immersed, cerebriform; conidiophores: type II sensu Vobis conidia: filiform, 15-18 µm long Spot tests: K+ yellow, C-, KC-, P+ orange Secondary metabolites: atranorin (major), chloroatranorin (minor), and zeorin (major). Substrate and ecology: on a range of different acidic rocks in open to partially shaded habitats at low to intermediate elevations World distribution: pantropical recorded from Africa, Asia, Australasia, North and South America, and the Pacific Area Sonoran distribution: occurring in scattered localities region in thorn forests and adjacent woodlands in Sonora, Sinaloa and Baja California Sur, and Chihuahua. Notes: Lecanora subimmersa has aspicilioid apothecia and is thus hardly confused with other Lecanora spp. in the Sonoran desert region, except L. comonduensis and L. oreinoides. The former, however, is easily distinguished since it consists of isolated areoles and the latter species differs in having a bullate thallus and black apothecial disc. Aspicilia spp. are readily distinguished by the different ascus-type and paraphyses.