Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: foliose, approximately circular in outline, medium to large, 10-15 cm in diam., adnate lobes: +flattened and elongate (1-1.5 cm wide and up to 7 cm long), often dichotomously branched, imbricate or separate; tips: rounded to subtruncate, often ascending and undulate upper surface: gray or blue-gray to brown when dry, bluish or greenish gray when wet, smooth, shiny, without soredia; marginally and laminally often phyllidiate phyllidia: warty to squamulose medulla: white, with +loosely interwoven hyphae photobiont: Nostoc lower surface: white, with anastomosing pale, smooth, raised veins that become dark brown towards center, rhizinate rhizines: white, darkening when old, fibrillose, bushy or penicillately branched, confluent Apothecia: common, +round to oblong, becoming saddle-shaped, on elongated, ascending lobes, up to 7 mm in diam. disc: pale to dark brown, smooth ascospores: colorless to pale brown, acicular, 3(5) septate, 40-57 x 3-5 µm Pycnidia: not seen in Sonoran material Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: among mosses on soil and over rock at relatively high elevation World distribution: Central and South America Sonoran distribution: rare in Sinaloa between Durango and Mazatlán at 2320-2740 m. Notes: Peltigera austroamericana is distinguished from other non-tomentose species in the area by its richly branched confluent rhizines and its lack of secondary metabolites. Phyllidiate morphs may remind one of P. fibrilloides but are completely without tomentum.