Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Thallus: superficial, continuous, thin, uneven, without a prothallus surface: pale brownish gray, smooth, dull anatomy: upper cortex 15-20 µm thick, with cells 3-5 µm in diam.; algal layer: 20-50 µm thick, with algae 5-8 µm in diam.; mycobiont portion (sub)paraplectenchymatous, composed of cells 3-5 µm in diam., without an alga-free medulla Perithecia: hemispherically prominent, laterally covered by thallus tissue with only the black tips bare; exciple: subglobose, 0.20-0.25 mm wide, colorless except for the apex, c. 20 µm thick; involucrellum: hemispherical, extending down to exciple-base level, diverging at base, c. 40 µm thick; periphyses c. 20 µm long, thin, simple asci: oblong-clavate, 60-70 x 17-23 µm, 8-spored ascospores: hyaline, simple, ellipsoid, 19-23 x 9-11 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on lignum (the type specimen), but on Quercus bark in the Sonoran specimen World distribution: Europe (Switzerland) and southwestern North America Sonoran distribution: montane areas of SE Arizona (Graham Co.). Notes: Verrucaria trabicola is a rare species yet known only from two collections.