Thallus: subfruticose, tufted, often forming loose cushions, (0.5-)1.5-2(-2.5) cm high, (0.5-)1-2(-4) cm in diam., usually formed from single plants, attached by a basal holdfast and cilia/rhizines lobes: at first stellate-radiate, 0.5 mm wide, soon becoming erect, often with branches reattached to each other by cilia, terminal parts bent upward, very variable in width both within and among specimens, 1-2.5(-8) mm wide, rigid, mostly flat to somewhat convex, dorsiventral, usually with ciliate tips upper surface: golden yellow, orange-yellow to pale orange (especially towards tips) or gray, dull to slightly shiny, smooth or weakly longitudinally ridged or wrinkled, rarely verrucose, usually with yellow, pale gray, or hyaline laminal and terminal cilia (likewise on side lobes); cilia: (0.07-)0.3-0.7(1.35) mm long, simple or more rarely branched lower surface: lighter in color than the upper, pale gray to white or yellow at the lobe tips, rarely entirely yellow, usually cracked in most parts exposing the medulla with remaining cortex strands forming a reticulate pattern, parts of the lower cortex usually regenerates, but a wrinkled or longitudinally veined pattern usually present, sometimes with a few short rhizines hairs: rare, straight, short (5-20 µm long), and mostly unbranched, consisting of single rows of cells soredia: very rare, farinose but soon becoming granular consoredia, yellow to yellowish green (even when the thallus is gray) in laminal, marginal or terminal (also on the lower side of both thallus and apothecia), erumpent, and mostly discrete soralia lobe anatomy: composed of three irregular layers upper cortex: prosoplectenchymatous, composed of +longitudinal hyphae, 10-90 µm thick or running through all the way to the bottom medulla: interrupted by cortex strands with algae in scattered groups, 40-130 µm thick lower cortex: prosoplectenchymatous, 0-90 µm thick or running all the way from top to bottom, having the same composition as the upper layer, with thin patches of medulla exposed where the cortex is missing; cortex hyphae: 1.5-3 µm thick with c. 0.5 µm thick walls, somewhat lax and separating (pretreated in K followed by water) Apothecia: almost always present, mostly terminal to subterminal but also laminal or submarginal, sessile to stipitate, (1-)2-5(-7) mm in diam., rather thin, often folding with age disc: orange-red, darker than thallus, concave when young becoming slightly concave to plane with age; thalline margin: yellow to pale gray, or sometimes becoming orange like the discs, entirely to somewhat crenulate, thin or somewhat thickened (especially at the attachment points of the cilia), slightly elevated, often becoming excluded with age, usually covered with numerous cilia asci: oblong to clavate, 45-60 x 15-18 µm, 8-spored ascospores: hyaline, polaribilocular, oblong to narrowly ellipsoid, 12-17 x 5-7 µm, septal width 4.5-7 µm Pycnidia: immersed to slightly protruding in orange warts, usually near the lobe tips but not always present, 0.1-0.15 mm in diameter conidia: narrowly ellipsoid, 3.5-4.5 x 1.5-2 µm Spot tests: K+ purple, C-, KC-, P- Secondary metabolites: anthraquinones: parietin (major), fallacinal, teloschistin, and parietinic acid (all minor), and emodin and erythroglaucin (both minor) (chemosyndrome A). Substrate and ecology: on oak in valley and foothill woodlands and coastal scrub, from sea level to 600 m World distribution: recorded from most parts of the world although lacking in Asia (but occurs in the western parts of the Arabian Peninsula), frequent in areas with Mediterranean climate of both hemispheres Sonoran distribution: rare in California (slightly more common on the Channel Islands), widespread in Mexico. Notes: The lower cortex often regenerates, but the reticulate pattern is usually still visible. Nearly all Sonoran material seen is ciliate, but in a few specimens cilia are almost absent. In these, a few cilia can be found either on the thallus or on some of the apothecia. Such specimens are not uncommon in Minnesota and Iowa. Narrow lobed specimens with few cilia and with very few cracks in the lower cortex are sometimes found near coastal, moist areas. Teloschistes chrysophthalmus is commonly attacked by the conspicuous lichenicolous fungi Spaerellothecium subtile, that forms a black network on the thallus, sometimes interspersed with small, black perithecia. The Sonoran region is apparently the only one in the world where sorediate specimens have been found and is apparently very rare [four specimens seen: Mexico, 10 km NNW of C. Constitutión, along route 1, 25°07.4'N 111°44.8'W; P & B. v. d. Boom 24908 (v. d. Boom priv. herb), 2 miles NW of Huatabampito, 26°43'N 109°35'W; T.H. Nash 12307 (ASU, B, and UPS), 1 mi NE El Arco, T.H Nash 8850 (ASU, C, and MIN), just S of San Carlos road (route 22), 16 km W of Ciudad Constitución; 24°59'N 111°51'W; T.H Nash 30431 (LD)]. It always grows among non-sorediate thalli of T. chrysophthalmus and is always parasitized by at least one or two lichenicolous fungi. It might be considered a different taxon. However, due to the rarity of specimens, overlapping ecology and distribution as well as the otherwise apparent similarity with non-sorediate specimens of T. chrysophthalmus, it is better to wait until more material is available and a molecular investigations have been conducted before making a decision. Teloschistes chrysophthalmus can be confused with T. hosseusianus Gyeln. (non-ciliated apothecia; only at high elevations in South America) and T. hypoglaucus (Nyl.) Zahlbr. (quadrilocular spores and broader lobes; in South America and Africa), none of which occur in the Sonoran region.