Thallus: foliose, loosely appressed to tightly adnate, large, 4-10(-15) cm wide, lobate lobes: linear to broadly sublinear, contiguous, plane, 2-11(-15) mm wide; apices: rounded upper surface: greenish yellow to yellow-green, turning a drab yellow to yellowish brown with age in the herbarium, smooth (especially at the margins) to weakly wrinkled and rugose, rarely weakly ridged-reticulate, sometimes with white maculae, rarely pruinose; rare specimens have small laciniae pseudocyphellae: white, common to occasional, seldom rare, small and punctiform to elongate, rarely up to 1 mm wide, occasionally elevated asexual propagules: none medulla: white with a continuous algal layer lower surface: black to dark chestnut brown, sometimes paler toward the margin, smooth to commonly finely wrinkled; rhizines: simple, rarely branching, short, concolorous with the lower surface, usually absent in a broad zone along the margins (as in Parmotrema spp.) Apothecia: common (but may be absent), lecanorine, sessile to substipitate and up to 10 mm in diam.; disc: pale to dark red-brown and deeply concave; exciple: often pseudocyphellate, usually continuous and smooth, entire to slightly undulating; epithecium: pale yellow-brown; hymenium: hyaline, hypothecium: hyaline asci: Lecanora-type; 8-spored ascospores: simple, hyaline, broadly ovoid to ellipsoid; 6-15 x 4-9 µm Pycnidia: black, usually common, laminal and concentrated toward the margins conidia: bifusiform, sometimes appearing filiform, c. 5-10 x 1 µm Spot tests: upper cortex K+ yellowish, KC-, C-, P-; medulla C+ red, KC+ red, K-, P- Secondary metabolites: usnic acid (minor), lecanoric acid (major), +5-chlorolecanoric acid (minor or trace). Substrate and ecology: on bark of hardwoods (Acacia, Acer, Alnus, Ceanothus, Fouquieria, Fraxinus, Ostrya, Plantanus, Prunus, Quercus, Salix), conifers (Abies, Cupressus, Juniperus, Pinus, Pseudotsuga) and rocks from 1200-2600 m. World Distribution: southwestern United States, Mexico, Peru, and East Africa (Kenya). Sonoran Distribution: in the mountains of southern Arizona, Chihuahua, Durango, Sinaloa, Sonora, and Baja California Sur at higher elevations. Notes: Flavopunctelia praesignis is more widely distributed in the United States and Mexico than F. darrowii. The thallus of F. praesignis is also generally thicker and more adnate to the substrate. Numerous spore and conidial measurements were made on both species, but no significant differences were found.