Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.

Life habit: lichenized Thallus: thin or evanescent, smooth or finely cracked, pale to dark gray Ascomata: 0.2-2.5(-4) x 0.2-0.5 mm, mostly elongate, sometimes oblong or rounded, infrequently branched, scattered or contiguous, sessile; disc a slit frequently broadening in maturity; exciple and/or disc sometimes + grey- or green-pruinose exciple: closed, K- hymenium: 60-80 µm, I+ red; epihymenium brown, K-; paraphysoids: branched, 1-1.5 µm asci: clavate, 50-70 x 15-18 µm (Varia-type) ascospores: 19-31(-33) x 5-6(-7) µm, 4-6(-7)-septate, the central cell distinctly enlarged (Varia-type); perispore hyaline, becoming dark brown when over-matured, 1-2 µm Pycnidia: often white or greenish pruinose conidia: 3-5 x 0.5-1.5 µm, straight or slightly curved Spot tests: thallus K-, C-, KC-, P-, UV- Secondary metabolites: no substances. Substrate and ecology: on neutral, basic, rough, shaded bark, especially of deciduous trees, occasionally on wood or decaying ferns, rare on sheltered limestone or mortar; on Sycamore bark in the Sonoran Desert Region World distribution: Europe, northern Africa, North America Sonoran distribution: California (Santa Barbara Co.) Notes: we have only seen one specimen belonging to this species from the Sonoran Desert Region where it seems thus to be very rare. Other specimens examined from the Sonoran Desert under this name were misidentifications for other Opegrapha species. According to Fink (1935), Opegrapha varia is distributed throughout the United States, but according to the distribution map of Brodo et al. (2001) the species is present in the half east as well as in the northwest of the United States. The description above is based on the literature.