Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: crustose, leprose or verruculose or verrucose-areolate; prothallus: not visible areoles: verruculose, thick, ecorticate surface: green to yellowish gray or yellowish brown, rough, covered with zeorin crystals giving a cottony appearance, yellowish pruinose, with a distinct, slightly sublobate margin, esorediate Apothecia: sessile to constricted at the base, 0.6-1.3 mm in diam., lecanorine disc: brown or gray-brown, plane, heavily gray to bluish gray pruinose margin: concolorous with thallus, thick, persistent, prominent, entire or flexuose, rough, verrucose or verruculose, without a parathecial ring amphithecium: present, with numerous algal cells, with large and small crystals, large crystals insoluble in K, corticated or ecorticate; cortex: indistinct, uniform, hyaline to pale yellow, interspersed with coarse crystals, 10-25 µm thick parathecium: hyaline, with small crystals, insoluble in K epihymenium: brown to yellowish brown, with pigment insoluble in K, with coarse crystals insoluble in K hymenium: hyaline, inspersed with oil droplets; paraphyses: not thickened (up to 2.5 µm wide) apically, not pigmented; subhymenium: hyaline, 15-20 µm thick; hypothecium: pale to deep yellow in K, inspersed with oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, broadly ellipsoid, 8-13.5 x 5.5-8 µm; wall: less than 1 µm thick Pycnidia: not seen Spot tests: K- or + pale yellow, C-, KC-, P- or P+ pale yellow Secondary metabolites: atranorin (minor or trace), usnic acid (major), zeorin (major), and unidentified fatty acids (minors). Substrate and ecology: on exposed siliceous rocks in thorn forests World distribution: endemic to SW North America Sonoran distribution: Baja California Sur, Sinaloa, and Sonora at elevations less than 1000 m. Notes: Lecanora pallidochlorina is a distinctive species characterized by a thick, somewhat cottony thallus that is covered with zeorin crystals and the heavily pruinose apothecial disc. The species is readily distinguished from other Lecanora s.str. species in the area that have heavily pruinose discs by the presence of usnic acid as major constituent.