Thallus: crustose, rimose to rimose-verruculose, thin, ±continuous; prothallus: absent or delimiting the thallus as a black outline where several different thalli meet surface: grayish white to dark gray, dull, epruinose, phenocorticate, esorediate medulla: white, lacking calcium oxalate (H2SO4-) Apothecia: lecideine; (0.2-)0.3-0.4(-0.5) mm in diam., soon sessile margin: black, thick, rarely persistent, usually excluded with age, rarely with a thalline veil when emerging from the thallus disc: black, epruinose, plane, soon becoming convex proper exciple: dispersa-type, inner excipular hyphae distinct, not reduced, pigmented, prosoplectenchymatous (textura oblita), extending from the deep reddish brown hypothecium (leptoclinoidesbrown, textura intricata), outer excipular hyphae short-celled, cells angular, distinctly 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, but sparse oil droplets from a weakly inspersed subhymenium; paraphyses: simple to moderately branched, apically swollen, with a brown pigment cap (cf. elachista-brown) asci: clavate, Bacidia-type, 8-spored ascospores: soon brown, 1-septate, occasionally with two additional false septa, narrowly ellipsoid, rarely constricted with age, with pointed ends, frequently slightly curved, (15-)18.5-[21.5]-24.6(27) x (5.5-)6.4-[7.6]-8.7(-10.5) µm (n=75); proper septum: becoming soon but only briefly thickened during spore ontogeny, lateral wall inconspicuously thickened (±Callispora-type); ornamentation: microrugulate (visible without DIC) Pycnidia: rare, urceolate to globose, unilocular; ontogeny similar to the Umbilicaria-type conidiogenous cells: mostly terminal, rarely also intercalary (cf. conidiophore-type V) conidia: elongate bacilliform, straight, 5.5-10.5 x 0.5-1 µm (n=42) Spot tests: K+ yellow to orange red (needle-shaped crystals if observed with the compound microscope), P- to weakly yellow, C- fluorescence: UV-(pale) iodine reaction: medulla non-amyloid Secondary metabolites: norstictic acid, traces of atranorin, dissectic, and stictic acid. Substrate and ecology: so far only found once on bark of Lysiloma, elsewhere also on wood World distribution: little known, although common at oceanic lowland localities in the eastern and southeastern USA Sonoran distribution: known only from the northeastern foothills of the Sierra La Laguna, Baja California. Notes: The species is similar to Buellia chloroleuca, but contains norstictic acid and lacks xanthones. It also has longer conidia and grows at low altitudes. It was originally described from North Carolina.