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

Thallus: crustose, areolate, thick, ±continuous; prothallus: absent or delimiting the thallus as a black outline where several different thalli meet surface: pale white to ivory, rarely beige, dull, smooth, epruinose, phenocorticate, esorediate medulla: white to faintly salmon colored, in parts with a distinctly rust-red, K+ purplish pigment (possibly chiodectonic acid), lacking calcium oxalate (H2SO4-) Apothecia: mamillana-type, initially lecanorine, but soon becoming lecideine; (0.3-)0.3-0.7(-1.5) mm in diam., soon sessile margin: brownish, blackening with maturity, thickening with maturity, inconspicuous in immature apothecia, but soon becoming distinct, initially emerging from the thallus with a ±well developed pseudothalline margin that becomes excluded with maturity disc: black, epruinose, plane, soon becoming convex proper exciple: first thin, indistinct but soon thickening, i.e., inner excipular hyphae distinct, hyaline but becoming pigmented with age, prosoplectenchymatous (textura oblita), extending from the deep reddish brown hypothecium (leptoclinoides-brown, textura intricata), outer excipular hyphae short-celled, cells angular, ±swollen (textura angularis) and ±carbonized with various amounts of a brown pigment (cf. elachista-brown, HNO3-) epihymenium: brown, pigmentation continuous with the outer exciple (HNO3-) hymenium: hyaline, not inspersed with oil droplets; paraphyses: simple to moderately branched, apically swollen, with a brown pigment cap (cf. elachista-brown) asci: clavate, Bacidiatype, 8-spored ascospores: soon brown, 1-septate, oblong to ellipsoid, not constricted, with obtuse ends, not curved, (14.5-)15.9-[17.1]-18.2(-19) x (7-)6.8-[7.8]-8.8(-11) µm (n=25); proper septum: narrow, not thickening during spore ontogeny (Buellia-type); ornamentation: faintly microrugulate or not visible in DIC Pycnidia: infrequent, globose, unilocular; ontogeny similar to the Umbilicariatype conidiogenous cells: mostly terminal, rarely also intercalary (cf. conidiophore-type V) conidia: elongate bacilliform, straight, 7-9 x 0.5-1 µm (n=30) Spot tests: K+ yellow-orange (crystals), P-, C-, reddish parts of the medulla K+ purple fluorescence: UV- (pale) iodine reaction: medulla non-amyloid Secondary metabolites: atranorin, divaricatic acid, norstictic acid and ±connorstictic acid, variolaric acid (J. A. Elix, HPLC), and an unknown rust-red pigment (possibly chiodectonic acid; not identified by HPLC but clearly visible in parts of the thallus). Substrate and ecology: currently only known from wood World and Sonoran distribution: possibly a subtropical species but currently known only from coastal Baja California Sur. Notes: The only other species in the Sonoran Region with a pigmented medulla are the saxicolous B. halonia and B. capitis-regum. All three species are easily distinguished, as they have very different secondary metabolite profiles. Buellia halonia is the only one with a yellow green thallus containing xanthones, distinctly reacting C+ orange. Buellia capitis-regum has muriform spores and an oil inspersed hymenium, whereas B. endoferruginea has 1-septate spores and lacks oil inspersion in the hymenium.