Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Thallus: crustose, weakly developed and barely visible, or well developed and distinctly lobate; prothallus: absent surface: white, faintly to coarsely pruinose, esorediate phenocortex: containing large amounts of calcium oxalate crystals (H2SO4+ needle shaped crystals) Apothecia: lecideine or lecanorine, up to 1.25 mm in diameter, occasionally emerging from the thallus with a distinct thalline margin and a concave disc, others re-emerging from damaged, previously grazed apothecia, lacking a thalline margin and developing a convex disc margin: black, initially covered with yellow crystals, disappearing when the margin becomes excluded with age disc: black, epruinose to slightly pruinose, concave to convex proper exciple: narrow, poorly differentiated, interspersed throughout with yellow crystals, aethalea-type, inner excipular hyphae narrow, hyaline, prosoplectenchymatous (textura oblita), often reduced, similar in structure and orientation to the paraphyses, transient with the deep reddish brown hypothecium (leptoclinoides-brown, textura intricata, c. 50 µm tall), outer excipular hyphae parallel, moderately swollen (textura oblita) and carbonized with a brown pigment (cf. elachista-brown) epihymenium: brown, pigmentation continuous with the outer exciple (HNO3-), inspersed with crystals hymenium: hyaline, not inspersed with oil droplets, more than 100 µm tall; paraphyses: simple to moderately branched, apically swollen, with a brown pigment cap (cf. elachista-brown, HNO3-) asci: Bacidia-type, clavate, 8-spored ascospores: soon brown, 1-septate, ellipsoid, slightly constricted at the septum, cell lumina thus appearing rounded, 16-24.5 x 10-12 µm; ornamentation: areolate (clearly visible at 200x magnification) Pycnidia: immersed, ostiole unpigmented at the thallus surface, pigmentation only visible in cross sections, ostioles thus barely visible as minute holes surrounded by yellow crystalline pruina conidia: filiform, strongly aggregated, c. 20 µm long, straight to slightly curved (e.g., Marsh 7474) Spot tests: C+ orange around the algal layer (thallus sections) Secondary metabolites: arthothelin (major), 4,5dichloronorlichexanthone, thiophanic acid (traces) (J. A. Elix, HPLC). Substrate and ecology: on calcareous soil, under semiarid conditions in open vegetation World distribution: originally described and previously known only from Australia and New Zealand Sonoran distribution: southern California (San Diego Co.). Notes: Buellia georgei is characterized by the presence of xanthones in the algal layer, a warty to areolate spore ornamentation, calcium oxalates in the thallus, filiform conidia, and its habitat. Due to these features the Sonoran material fits well into the "Buellia epigaea-group" (Grube et al. 2004, Trinkaus and Mayrhofer 2000), apparently most closely related to Buellia epigaea, B. dijiana, and B. georgei. The two specimens which have been investigated here are anatomically very similar but differ morphologically. The thallus of the Marsh specimen 7474 is much better developed, lobate and rather thick, whereas the Tuckerman specimen is very small with a thallus consisting of a few tiny squamules. Typical specimens of Buellia georgei are much better developed, and they have a chalky white thallus and rather big, coarsely pruinose apothecia. The apothecia of the two specimens analyzed are almost epruinose. More material is needed to clarify the taxonomic position of the two specimens that were available for this study. For now, they are retained within a broad concept of B. georgei s.l. A further collection that also was available for study is problematic. This collection by Cooper (s.n., 1865) contains both a specimen of B. bolacina and B. georgei. The original collection is labeled B. bolacina, but a second specimen, B. georgei, was apparently included at a later date. Collection notes for the two specimens within the same packet are mixed up and it appears that both specimens originate from different localities, collected at different times.