Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: foliose, small to medium-sized, 5-7 cm in diam., adnate lobes: elongate, up to 5 cm long and 5 mm wide, with up-turned, curled and often somewhat phyllidiate margins upper surface: gray or blue-gray to brown when dry, blackish green when wet, tomentose marginally, dull to somewhat shiny centrally, often pruinose marginally, often marginally or laminally phyllidiate phyllidia: warty to squamulose, often pruinose medulla: white, with +loosely interwoven hyphae photobiont: Nostoc lower surface: white, marginal parts with anastomosing white and raised veins that become flattened and reddish-brown towards center, rhizinate rhizines: short, pale and +simple to fasciculate near margins, darkened and tufted towards center Apothecia: +round, flat or saddle-shaped, on short lobes, up to 5 mm in diam.; margin: smooth to crenulate disc: flat, brown, smooth ascospores: colorless to pale brown, acicular, 3(-5) septate, 39-52 x 4-5 µm Pycnidia: not seen in Sonoran material Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on soil among and over mosses World distribution: temperate and boreal regions of North America, Europe and Asia Sonoran distribution: frequent in Arizona, southern California, Baja California Sur, and Chihuahua. Notes: The relationship of P. monticola to P. ponojensis requires additional study. A morph without tomentum, and often with entirely brownish thalli and perhaps more elevated veins is tentatively included here, but its true relationship requires further investigation.