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Xanthoparmelia nigropsoromifera (T.H. Nash) Egan, (1976)
Family: Parmeliaceae
Xanthoparmelia nigropsoromifera image
Stephen Sharnoff  
Thallus: foliose, adnate, 3-7 cm in diam., irregularly lobate lobes: subirregular, elongate, plane to subconvex, separate and contiguous, 1.5-3 mm wide, not lobulate; apices: subrotund, smooth to crenate, eciliate upper surface: yellow to yellow-green, smooth but becoming strongly rugose with age, dull to slightly shiny, epruinose and emaculate, without soralia, isidia, or pustulae medulla: white, with continuous algal layer lower surface: black, plane, sparsely rhizinate; rhizines: black, simple, 0.2-0.5 mm long Apothecia: common, adnate to substipitate, 1-6 mm wide, laminal on thallus; disc: cinnamon-brown to dark brown; margin: smooth, epruinose asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 7-8 x 4-5 µm Pycnidia: common, immersed conidia: bifusiform, 5-6 x 1 µm Spot tests: upper cortex K-, C-, KC-, P-; medulla K-, C-, KC-, P+ yellow Secondary metabolites: upper cortex with usnic acid (major); medulla with psoromic acid (major), 2'-O-demethylpsoromic acid (minor), and usually subpsoromic acid (trace). Substrate and ecology: on acidic rocks, often in open, arid to woodland habitats World distribution: southwestern North America Sonoran distribution: occasional at low to intermediate elevations in Arizona, Chihuahua and Sonora. Notes: Xanthoparmelia nigropsoromifera is very similar to X. psoromifera, but the latter differs in having a pale brown lower surface. It is also related to X. huachucensis, which has a black lower surface and identical chemistry, but has much narrower lobes (0.4-1 mm vs. 1.5-3 mm wide).