Thallus: orbicular to irregular, up to 2 cm diam., usually confluent with other thalli forming bigger patches, ± loosely adnate to the substrate lobes: flat to weakly concave, up to 1.5 mm wide, usually around 1 mm, sparsely branched with ± spreading, truncate lobes, eciliate upper surface: whitish gray to dark gray, ± shiny and without pruina, sorediate soredia: granular (inner parts almost isidiate), in marginal soralia upper cortex: paraplectenhymatous medulla: white, thin lower cortex: paraplectenhymatous lower surface: whitish with few, robust, pale rhizines Apothecia: not common, seen only in the type material, up to 1.5 mm diam. ascospores: brown, 1-septate, sparsely developed, Pachysporaria type, 18-22 x 9-11 µm Pycnidia: not common, immersed, appearing as black warts conidia: subcylindrical, 4-6 x 1 µm Spot tests: upper cortex K+ yellow, C-, KC-, P+ yellow; medulla K-, C-, KC-, P- Secondary metabolites: upper cortex with atranorin (sometimes extending into algal layer but not below into the thin medulla). Substrate and ecology: growing on open rocks, especially sandstone World and Sonoran distribution: so far known only from low to intermediate elevations of southern California, Baja California Sur, Chihuahua and Sonora. Notes: Physcia neglecta is a distinctive species recognized by the truncate, loosely adnate, spreading lobes, the granulose, well delimited soralia and the precence of atranorin only. It might be confused with P. nashii which is smaller, has convex lobes, soralia on lobe tips, and a prosoplectenchymatous lower cortex. As in P. nashii the K reaction in the medulla is sometimes yellow in spite of absence zeorin.