Thallus: foliose, up to 4 or 5 cm in diam., often +irregular, but sometimes orbicular lobes: rounded-crenate to somewhat elongate, 0.4-1 mm broad, flat to weakly concave, prostrate upper surface: olive brown to rather dark brown on edges, epruinose, usually moderately to strongly shiny on the lobe ends, isidiate isidia: laminal, globose to more often cylindrical and sparsely branched, 0.05-0.15 µm in diameter, occasionally bearing pycnidia (not at tip), sometimes becoming crowded and +continuous in older thallus parts upper cortex: paraplectenchymatous medulla: white lower cortex: paraplectenchymatous lower surface: tan to pale brown, dull; rhizines: sparse, simple, concolorous with the lower surface Apothecia: rare, up to 1 mm in diam.; margin: becoming isidiate ascospores: ellipsoid to ovoid, 7-9 x 5-6.5 µm Pycnidia: occasional, immersed to weakly emergent, black, submarginal or on the isidia conidia: bifusiform, 4-5 x 1 µm Spot tests: cortex and medulla all spot tests negative Secondary metabolites: 2-3 high Rf lichesterinic acid type fatty acids. Substrate and ecology: most common on wood, also on conifer bark World distribution: southwestern North America Sonoran distribution: Arizona, Sonora and Chihuahua. Notes: As an isidiate species, Tuckermanella coralligera stands out in the genus. Occasional specimens of T. fendleri are laciniate and/or papillate-foliolate and these might be mistaken for T. coralligera, but the papillae or folioles in T. fendleri are less regular than the isidia of T. coralligera and they bear pseudocyphellae.