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

Life habit: lichenized Thallus: well-developed, granular to verrucose, pale gray to green Apothecia: with a distinct white pruina on the outer surface of the exciple, 0.3-0.4 mm tall, 1.5-2.5 times as high as the width of the stalk stalk: short, 0.11-0.14 mm wide, consisting of dark brown, irregularly interwoven and strongly sclerotized hyphae, becoming pale towards surface; outermost layer: paler and forming a distinct, gelatinous, hyaline coat capitulum: obovoid to lenticular, 0.19-0.31 mm in diam. exciple: dark brown to aeruginose, composed of almost isodiametric sclerotized cells, paler in outer part; hypothecium: dark brown with flat or slightly convex upper surface asci: cylindrical, 39-41 x 5-6 µm, with uniseriate spores ascospores: semi-mature spores: smooth; mature spores: ellipsoid, 10-11.5 x 5-6 µm, with a coarse irregular ornamentation of irregular cracks, but no ridge fragments Spot tests: thallus K-, C-, KC-, P-; apothecia I- Secondary metabolites: divaricatic acid and 2-O-methyldivaricatic acid. Substrate and ecology: on wood, in Pinus ponderosa forest World distribution: Africa, Europe, North America Sonoran distribution: one collection from Arizona on trunk of dead and decorticated Juniperus deppeana at 2640 m. Notes: Calicium montanum is characterized by its often very thick, verrucose and slightly granular thallus, its sturdy, short-stalked, pruinose apothecia, and its medium-sized spores, which are smooth when young and have a coarse ornamentation of irregular cracks when mature.