Thallus: crustose, uniform, thin, continuous, with +scattered, +round verrucules, c. 0.1-0.3 mm in diam., esorediate; prothallus: not visible surface: glaucous white, in herbarium turning yellowish gray, unchanged when wet, smooth, dull, epruinose cortex: a hyaline phenocortex, weakly inspersed with fine granules (soluble in K), overall 30-50 µm thick; overlain by a thin, indistinct epinecral layer medulla: not developed; algal layer: algae globose, rarely ellipsoid, simple, 7-10(-14) µm in diam., thick walled Apothecia: dispersed or contiguous, large, cyathiform, sessile, constricted at base, with conspicuously elevated or subpedicellate bases, 0.8-1.5 mm in diam. disc: white-carneous, light grayish yellowish brown to pale yellowish pink or paler, concave to plane or slightly convex, epruinose to densely but very finely pruinose, scarcely changed when wet, dull margin: bare and grayish yellow to moderate yellowish brown, or pruinose and concolorous with disc, persistent, thick, 0.1-0.2(-0.3) mm wide, slightly to strongly raised and inflexed, entire or becoming distinctly flexuous and crenate towards inside, lumpy and uneven (almost shallowly foveolate) in places, often abraded amphithecium: with a cortex up to 100 µm thick, pale yellow, composed of densely intricate hyphae, conglutinate and gelatinous, with an algal layer present in margin below cortex and extending below hypothecium, with a non-cellular medulla up to 200 µm thick parathecium: narrow, gelatinous, up to 10 µm high epihymenium: brown to reddish brown, densely interspersed with granules, without amorphous surface layer hymenium: hyaline, 40-65 µm tall; paraphyses: simple to branched, 1-1.5 µm in diam. below, apically not thickened or sometimes slightly clavate and 2.5-3 µm in diam., not pigmented; hypothecium: hyaline, with unoriented hyphae, with rounded to elongated cells c. 5 µm in diam. and with lumina c. 5 µm wide asci: oblong-clavate, Catillaria-type, 30-40 x 8-12 µm, 8-spored ascospores: hyaline, biseriate, 1-septate, oblong, straight or slightly curved, not constricted, apices rounded to obtuse, becoming 3-septate when mature, 9-15 x 3-3.5 µm Pycnidia: abundantly present and visible as irregular black dots, c. 0.3 mm wide; conidiogenous cells: short and branched conidia: short bacilliform, pleurogenously formed, 3-4 x 1 µm Spot tests: thallus K+ yellow, C-, KC-, P- Secondary metabolites: gangaleoidin (major), atranorin (submajor), norgangaleoidin (minor), 3-dechlorogangaleoidin (minor), chlorolecideoidin (minor) and chloroatramorin (minor) [determined by J.A. Elix by HPLC]. Substrate and ecology: on bark of trees and shrubs World distribution: southwestern U.S.A. and northwestern Mexico Sonoran distribution: southern California, from San Luis Obispo Co. in the north to Baja California (north) as the southern limit. Notes: Solenopsora cyathiformis is a very distinctive species due to its relative large apothecia, but it is easily overlooked in the field by assuming that it is Lecanora sp., especially L. pacifica. Lecania fuscella may be superficially similar but differs in a number of anatomical differences, as well as chemistry (see notes under that species). Solenopsora cyathiformis definitely does not belong to Lecania s. str., in which it originally was described, because of its Catillaria-type asci, bacilliform conidia 3-4 x 1 µm, and its different chemistry. This is the first corticolous species of the multiform genus Solenopsora. Most of the known species on rocks of the genus have a granular, squamulose or lobate thallus. The apothecia in specimens of S. bagliettoana, S. candicans and S. cesatii have been compared, and they show considerable similarity to those of S. cyathiformis. The chemistry of the genus is not sufficiently known; there are various unidentified metabolites, some species contain pannarin, and atranorin is also known from Solenopsora.