Thallus: crustose, thin, ±continuous, ±rimose to areolate surface: almost white or ±gray, wrinkled or warted, never dissolving into soredia Apothecia: at first flat, later becoming convex, 0.3-0.7 mm in diam. disc: pale pink, pale yellow, pale orange, pale to medium brown-orange or orange-brown, or pale to dark red-brown, often piebald, epruinose margin: at first distinct, level with or raised above disc, finally excluded, usually paler than disc but sometimes concolorous; when young with a rather thin thalline portion covering most or all of the exciple, soon excluded but remaining clearly visible in section, concolorous with thallus exciple: laterally 25-85 µm wide, without crystals, colorless or very pale yellow, sometimes with a darker yellow (K+ intensifying) or pale to dark red-brown (K+ purplish, N+ orange) rim, often gradually fading below epithecium: colorless to pale brown to red-brown (K+ purplish, N+ orange), without crystals hymenium: hyaline or diffusely pale yellow (K+ intensifying), 55-70 µm tall; paraphyses: 1.2-2(-3.2) µm wide in mid-hymenium; apices: ±clavate or sometimes only slightly or not at all swollen, 1.6-5.3 µm wide hypothecium: colorless or very pale yellow (K- or K+ intensifying) asci: clavate, 8-spored, Bacidia-type derivative with no ocular chamber and a very wide axial body ascospores: hyaline, 3- to 7septate, acicular, straight or slightly curved to sigmoid, 2557 x 1.2-2.5 µm Pycnidia: immersed in thallus, colorless, conidia: filiform, curved, non-septate, 9-16 x c. 0.5 µm Spot tests: all negative Secondary metabolites: none detected. Habitat and ecology: mainly on smooth bark of twigs, branches and young trunks of shrubs and broad-leaved trees, occasionally also on coarse bark of tree trunks, in open and well-lit habitats like scrubs, forest edges, and open forests from sea level to c. 1300 m in the San Gabriel Range World distribution: western North American from southern California to Vancouver Island Sonoran distribution: scattered records from the Channel Islands and coastal mainland California. Notes: Bacidina ramea can be readily identified by its unique, thin thalline margin, which, although externally visible only in young apothecia, remains easily observable in sections of older apothecia. Molecular evidence indicate that Bacidina ramea does not belong to Bacidina and is instead closer to Lecania s. lat (Ekman unpubl.).