Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: foliose, 2-4 cm in diam., adnate, subdichotomously to irregularly lobate lobes: irregular, elongate, +plane, separate, 3-5 mm wide, 200-500 µm thick; margin: sometimes turning under; apices: rotund, entire to irregularly cut upper surface: medium gray to brown or olivaceous brown, usually dull, distinctly wrinkled, not isidiate internal anatomy: with upper and lower cortices consisting of a single layer of irregularly isodiametrical cells 3-5 µm in diam., internally with loosely interwoven chains of Nostoc and hyphae lower surface: pale gray or brown, heavily wrinkled, with scattered tubercular outgrowths Apothecia: common, laminal, sessile, 1-2 mm wide disc: brown to red-brown, concave to plane margin: thalline, concolorous with the thallus or tan, entire exciple: euparaplectenchymatous, 90-100 µm thick centrally hymenium: hyaline below and thinly brown above, 125-135 µm tall; paraphyses: unbranched, c. 1.5 µm wide, slightly inflated apically; subhymenium: pale yellow, 35-45 µm thick asci: cylindrico-clavate, 8-spored ascospores: hyaline, submuriform to muriform, 3-5-septate transversely, 1-septate longitudinally, ellipsoid to fusiform, 25-35 x 7-10 µm Pycnidia: not observed Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on non-calcareous rocks and tree bases World distribution: Mexico and southwestern U.S.A. Sonoran distribution: Arizona, Chihuahua, Sonora, and Sinaloa. Notes: Leptogium hypotrachynum is a poorly known species in the L. azureum group, and is characterized by its rather thick thallus and its unusual tubercular outgrowths on the lower surface, that are unique among the Sonoran species of Leptogium.