Thallus: crustose, indistinct, thin, areolate areoles: dispersed to aggregated (especially in vicinity of apothecia), ecorticate but sometimes corticated with a loose unorganised alga-free layer of various hyphae surface: pale yellow to yellowish brown, sometimes slightly to moderately pruinose, esorediate Apothecia: occurring in groups, rarely single, broadly sessile to constricted at base, 0.3-1.1 mm in diam. disc: pale brown to reddish brown, smooth, flat, epruinose or slightly pruinose margin: even with disc, smooth, uniform, slightly to moderately white pruinose, paler than thallus and disc, without a parathecial ring amphithecium: present, with sparse algae, ±60 µm thick, corticate; cortex: indistinctly or ±distinctly delimited, uniform or slightly thicker at the base than at the sides, 25-30 µm thick laterally, 30-45 µm thick at base, composed of adglutinated, gelatinous hyphae; cortical granules: sparse and mostly at top of margin (pol+, insoluble in K, soluble in N) parathecium: indistinct to well delimited and 10-30 µm wide epihymenium: shades of yellow or brown, with superficial, coarse granules (pol+, partly soluble in K but most insoluble in K and in N) between the paraphyses tips (some also in hymenium) hymenium: hyaline, 60-70 µm tall; paraphyses: slender, somewhat branched throughout, with few anastomoses; subhymenium: hyaline, indistinct, ±granulose, 15-20 µm thick; hypothecium: hyaline, prosoplectenchymatous, clear, without granules, 100-120 µm thick asci: clavate, 8-spored ascospores: hyaline, simple, narrowly ellipsoid to ellipsoid, 10.4-13.3(-14.8) x 4.5-5.9 µm Pycnidia: not seen Spot tests: thallus K+ yellow, C+ orange, KC+ orange, P+ orange; apothecial margin and disc K+ yellow, C+ yellow or C-, KC+ orange, P+ orange; apothecia UV+ yellow-orange Secondary metabolites: unknown xanthone (Rf 4-5), ±pannarin. Substrate and ecology: on siliceous rocks (granite, rhyolite) along seashores World distribution: western North America and Europe Sonoran distribution: southern California (Santa Rosa Island) and Baja California Sur. Notes: The members of L. fugiens complex are separated from L. dispersa by their more abundant thalli, distinct P+ orange reaction of the apothecial discs and usually positive K and C reactions of the thallus and apothecia. Lecanora fugiens has been recently recognized as occurring in the northeastern part of North America. Sonoran material seems to be related to that population due to its similar spot tests reactions and ecology. There are, however, some morphological details (e.g. more abundant thallus, larger, aggregated apothecia), which suggest that some other species of the group may be included here. For example, L. andrewii de Lesd. in M'Andrew may be an appropriate name for the west coast material, but because the original type of the de Lesdain material was presumably destroyed at Dunkirk, no assessment was possible.