Thallus: crustose to squamulose, areolate to subsquamulose, up to 4 cm across, 0.2-1 mm thick areoles: irregularly separated by broad fissures, 1-3 mm wide squamules: +round to irregular or coarsely crenate, more distinctly lobed peripherally, contiguous, convex, plane to uneven or +undulate with edges level or slightly raised, incised at margin, 0.5-1.5 mm across, with raised convex areas upper surface: dark brown to dark grayish brown or dark blackish brown, reddish brown when wet, edges partly paler, dull to slightly shiny, epruinose upper cortex: upper part deep red-brown pigmented, not interspersed, overall (35-)50(-75) µm thick, with prosoplectenchymatous, anticlinal hyphae with lumina 2-3 x 1-2 µm, overlain by an epinecral layer (10-)20-30(-50) µm thick medulla: with indiscernible hyphae; algal layer: 75-100(-150) µm high, +continuous; algal cells: 5-15 µm in diam. lower cortex: hyaline, 15-20 µm thick lower surface: poorly developed towards the margin, pale orangish yellow to white Apothecia: rather numerous, erumpent, laminal, adnate to sessile, rarely somewhat constricted at base, 15 per areole, 0.5-1.3 mm in diam. disc: brownish black, unchanged when wet or sometimes redder and dark-spotted, flat to slightly concave, when young slightly rugulose, dull, epruinose margin: thalline, chocolate brown or dark reddish brown, gradually paling downwards, flexuous to crenate from the beginning, later becoming wavy, 0.1-0.2 mm wide, persistent, +raised amphithecium: lateral parts with brown pigmented unoriented hyphae, lower parts becoming a small rim of unoriented hyphae; algal layer: irregular, up to 120 µm thick parathecium: paler and redder than disc, +conspicuous from above, 25-50 µm thick laterally, paraplectenchymatous, with strongly conglutinated cells with lumina 2-6 µm in diam. epihymenium: dark brown to reddish brown, continuous, non-granular hymenium: hyaline, 50-80 µm tall; paraphyses: conglutinate, 1.5-2.5 µm in diam. below, with cylindrical cells 7-12 µm long, apically clavate and up to to 5 µm wide, the upper part bound in a strong gelatinous matrix; hypothecium: hyaline, up to 80 µm thick, with intricate hyphae in upper part, paraplectenchymatous below asci: clavate, Bacidia-type, c. 60 x 12 µm, 8-spored, ascospores: hyaline, straight or slightly curved, 0-1-septate, the septum sometimes faint cylindrical, oblong or some slightly oblong-fusiform, (16-)18-22 x 3.5-4.5(-5) µm, Pycnidia: c. 120 µm wide and 250 µm tall, hyaline below; ostiole: up to 150 µm, roughened, dark red-brown; conidiogenous cells: cylindrical elongate, branched, c. 1.5 µm in diam. conidia: filiform, curved, 17-25 x c. 0.8 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on acidic rock (sandstone) World and Sonoran distribution: southwestern California in the Santa Monica Mountains. Note: The description of L. hassei is based on the holotype from W and various collections in other herbaria, all made by Hasse, and very similar to the holotype; however, no recent collections of the species have been seen by us. The only accompanying species is cf. Lecanora muralis (only some sterile parts). Lecania hassei is characterized by its long, narrow ascospores, its dark, subsquamulose thallus and its paraphyses tips, that are bound in a strong gelatinous matrix. Species in the Sonoran region, with which it might be confused, are L. brunonis, that has shorter ascospores and generally a paler thallus, L. toninioides, that also has a paler thallus usually with distinctly pale edged squamules. Lecania brattiae has a squamulose but paler thallus with grayish edges and shorter ascospores; L. dudleyi has a more bullate thallus, that is often pale with a yellowish tinge. Although the protologue describes the conidia as being linear, straight, 8-10 µm long, all material seen by us and according to Zahlbruckner's notes and drawings on the isotype in FH, and also according to Noble (in Ahti, et al. 1987) support the interpretation, that L. has-sei has filiform, curved, much longer conidia. Furthermore, according to the protologue, the thallus is squamulose and imbricate specimens are subsquamulose and contiguous.