Thallus: rimose-areolate to verrucose, with flat to bullate, moderately thick verrucae; margins: unzoned to seldom zoned upper surface: whitish gray to whitish green, smooth to rugose, dull to slightly glossy, epruinose to slightly grayish pruinose soredia: granulose, 20-25 µm in diam., soredial margins indefinite, occurring in numerous, orbicular soralia, 0.5-1.6 mm in diam., whitish gray Apothecia: no fertile specimens seen Pycnidia: not seen Spot tests: K+ yellow, C-, KC-, P+ yellow, UV+ yellow Secondary metabolites: haemathamnolic acid and lichexanthone (both major), decarboxythamnolic, hypothamnolic and thamnolic acids (all minor). Substrate and ecology: rather common on siliceous rocks (including conglomerate or rhyolite) in mountainous areas World distribution: endemic to North America from central Mexico to SW U.S.A. Sonoran distribution: coastal California and inland from southern Arizona, Sonora and Chihuahua, primarily at 1200 to 2300 m. Notes: Pertusaria moreliensis is a sorediate species which can be distinguished from other saxicolous sorediate Pertusaria species in the area by its whitish gray thallus and the presence of lichexanthone (UV + yellow), while other sorediate taxa (sorediate morphotypes of P. flavicunda and P. tejocotensis) contain thiophaninic acid (UV + orange) and have a yellowish thallus. Morphologically similar to P. moreliensis is P. excludens Nyl. which differs in containing a norstictic acid chemosyndrome and having usually smaller soralia. Another saxicolous species with lichexanthone (UV + yellow) in the area is P. mariae, which is easily distinguished by the absence of soralia and the presence of norstictic acid.