Thallus: foliose, 3-10(-15) cm in diam., loosely adnate, irregularly lobate; lobes: irregular, somewhat elongated, often lobulate, often flabellate or lobulate, +plane, separate, 3-15(-20) mm wide, 100-200 µm thick; apices: rotund, entire to crenate, occasionally upturned; upper surface: medium gray to more typically bluish gray, dull to somewhat shiny, somewhat wrinkled; internal anatomy: with upper and lower cortices consisting of a single layer of irregularly isodiametrical cells, internally with loosely interwoven chains of Nostoc and hyphae; lower surface: pale to medium gray, smooth, with dense white tomentum of cylindrical hairs up to 0.1 mm long; Apothecia: frequent, laminal, stipitate, 1-2 mm wide; disc: brown to red-brown, plane to convex; margin: thalline, concolorous with the thallus, rugulose, often pubescent; exciple: euparaplectenchymatous, 20-25 µm centrally; hymenium: hyaline below and thinly brown above, 100-130 µm tall; paraphyses: unbranched, 1-2 µm wide, slightly inflated apically; subhymenium: pale yellow, 50-60 µm thick; asci: cylindrico-clavate, 8-spored; ascospores: hyaline, submuriform, 3-4-septate transversely, 0-1-septate longitudinally, ellipsoid with acuminate ends, 25-35 x 10-12 µm; Pycnidia: not observed; Spot tests: all negative; Secondary metabolites: none detected.; Substrate and ecology: on bark; World distribution: North, Central and South America and Japan; Sonoran distribution: montane areas of Chihuahua.; Notes: Leptogium acutisoporum is somewhat similar to L. rugosum, but the former has a bluer, less strongly wrinkled thallus as well as ellipsoid spores.