Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.

Thallus: continuous to finely fissured or fissured-areolate, with very thin to thin verrucae; margins: entire, unzoned upper surface: yellow-gray to green-gray, smooth to finely tuberculate, shiny, seldom dull, epruinose; lacking soredia or isidia fertile verrucae: concolorous with thallus, ampliariate or erect, numerous, c. 0.3-1.4 mm in diam.; ostioles: 1 or 2-8 per verruca, level, sunken or papillate, often fusing in a central depression to form a pseudolecanorate disc Apothecia: 1-5 per verruca; disc: 0.4-0.8 mm wide, blackish brown, epruinose; epithecium: dark brown to black, K; hypothecium: hyaline asci: cylindrical, 160-320 x 35-60 µm, 2-spored (seldom 1- or 3-spored) ascospores: hyaline, ellipsoid to cylindrical, 45-160 x 26-48 µm; spore wall: 2-layered; outer spore wall c. 1-5 µm thick; inner spore wall: 2-8 µm thick, smooth; apices: up to 20 µm thick Pycnidia: immersed conidia: bacilliform, 9-16 x 1-1.5 µm Spot tests: K+ yellow, C+ orange, KC-, P+ yellow to orange, UV+ orange-red Secondary metabolites: 2-chloro-6-O-methylnorlichexanthone and stictic acid (both major), 4-chloro-6-O-methylnorlichexanthone, constictic, cryptostictic, hypostictic, menegazziaic, thiophaninic acids (all minor). Substrate and ecology: A temperate corticolous species World distribution: Pertusaria pustulata is a cosmopolitan corticolous lichen Sonoran distribution: only known from southern California. Notes: This species is characterized by a greenish to yellowish thallus, ascomata with ostiola which may dilate and fuse to form a small pseudolecanorate disc, a K- epithecium, 2-spored asci and the presence of stictic acid and 2-chloro-6-O-methylnorlichexanthone. A full discussion of this species is found in Dibben (1980) and Archer and Messuti (1997).