Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.

Thallus: small foliose, up to 1 cm wide or coalescing to form extensive colonies, adnate to ascending to erect, often with a shrubby appearance lobes: dorsiventral but often convex and twisted, imbricate, narrow 0.1 -0.6 mm wide upper surface: lemon yellow to orange yellow, in shade paling to yellow green, smooth to somewhat coarse soredia: granular, blastidious, marginal or from the lobe tips and from the lower side of the lobes upper cortex: c. 10-45 µm thick (may reach through the whole thallus) medulla: white, very thin lower cortex: lacking or partly lacking, c. 5-20 µm thick lower surface: arachnoid at least in parts, white or more often greenish when algal layer is exposed, sparsely rhizinate; rhizines: short, white and simple Apothecia: fairly common, laminal, sessile, up to c. 1 mm diam.; margin: smooth but often sorediate or lobulate; disc: concolorous with or darker yellow than thallus; epithecium: c. 5-10 µm thick; hymenium: c. 45-85 µm tall; paraphyses: simple, cylindrical or with somewhat swollen, up to 3 µm wide tips; hypothecium 50-70 µm thick asci: clavate, 8-spored ascospores: oblongnarrowly ellipsoid, often somewhat curved, with numerous oil-droplets, colorless, 11-16 x 4-6 µm Pycnidia: common, appear as raised orange warts on the surface conidia: ellipsoid, 2.5-3.5 x 1.5 µm Spot tests: upper surface K- (or + deeper yellow-reddish), C-, KC-, P-; medulla K-, C-, KC-, P- Secondary metabolites: not investigated but probably similar to the other Candelaria species (i.e. containing calycin and pulvinic dilactone). Habitat and ecology: on bark or wood, rarely on rocks World distribution: known from westernmost North America up to Washington and Idaho Sonoran distribution: mainly on twigs of exposed trees and shrubs at low elevations in the desert up to at least 1500 m in open woodlands in southern California and Baja California. Notes: Candelaria “pacifica” is apparently an undescribed species, that differs from C. concolor in spore number and in the production of soredia from the lower side, which mostly lacks a cortex. Its erect habit with convex and often twisted lobes, together with the contrasting greenish color of the soredia produced from the lower side, gives this undescribed species a rather characteristic appearance. The lobe morphology is, however, rather variable and the thalli may sometimes form isidiate-sorediate crusts in a similar way to C. concolor. Candelaria “pacifica” is used as an interim name here because material from Europe has also proved to be similar. Thus, the synonyms of C. concolor need further investigation before the nomenclatural status of this taxon can be resolved (Westberg, in prep.)