Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: verrucose, well developed, variable in thickness, sometimes almost immersed surface: intensely yellowish green cortex: 14-15 µm thick, with numerous minute yellowish green crystals Apothecia: immersed in verrucae, epruinose, 0.5-0.8 mm in diam mazaedium: 0.3-0.5 mm in diam., black, epruinose exciple: uniformly thin, rim-like, thin throughout, 14-30(-40) µm thick laterally and not or only slightly thickened at the base, blackish brown, sclerotized, irregularly arranged and strongly intertwined hyphae with thickened walls hypothecium: 55-85 µm high, medium brown, with strongly intertwined hyphae asci: pyriform, 18-22 x 6-7 µm, rupturing at very early stages, with 2-3-seriate spores ascospores: brown, 1-septate and constricted in the middle, broadly ellipsoid, 17-21 x 9-11 µm; surface: smooth, without cracks Pycnidia: at first spherical to ellipsoid, 160-190 x 105-125 µm, later irregular and confluent with other pycnidia to leave incomplete walls deliminating aggregates of numerous loci; pycnidium aggregates: irregular, up to 0.4 mm wide, sometimes opening by a few longitudinal slits; wall: 9-12 µm thick, consisting of isodiametric or slightly elongated, moderately sclerotized, medium brown cells; in the uppermost part: cells spherical, 4-5 µm in diam. and heavily sclerotized, blackish brown; conidiophores: short, with few branches; basal cells: +isodiametric, 3-4 µm; conidiogenous cells: ellipsoid to short cylindrical, 2.5-4 x 1.5-2.5 µm, terminal and branched conidiophores also produced laterally conidia: non-septate, hyaline, ellipsoid, 3-4 x 1.5 µm Spot tests: thallus K-, C-, KC-, P- Secondary metabolites: thallus with rhizocarpic acid, epanorin and two unidentified metabolites. Substrate and ecology: on dry, weathered wood or rarely bark, especially of conifers (Pinus and Picea) or occasionally Betula, and post and rails in old forests World distribution: widely distributed in the boreal and temperate zones of Eurasia and North America Sonoran distribution: southern California, Arizona, Baja California Sur, Chihuahua, Sinaloa, and Sonora. Notes: Occasional specimens of Cyphelium tigillare with a pale thallus, lacking rhizocarpic acid, occurring at higher altitudes and latitudes, can be difficult to distinguish from