Thallus: cracked-areolate, forming small patches or extensive thalli up to several centimeters across, 0.2-0.3 mm thick, with rather acute fissures, sometimes bordered by a dark, compact or fimbriate prothallus areoles: angular, plane, 0.1-0.4 mm wide, with brown to black side-walls surface: gray to grayish brown, usually whitish gray pruinose, minutely wrinkled or roughened, thinly black-rimmed or not, dull anatomy: upper cortex: composed of few layers of 4-6 µm in diam. cells, with a 10-20 µm thick amorphous epinecral layer; algal layer: filling most of thallus, paraplectenchymatous, composed of cells 4-6 µm in diam., with algal cells 6-12 µm in diam.; basal layer: thin, brown to black, discontinuous, or lacking Perithecia: mostly at the margins of, or between the areoles, but also submarginally oder centrally immersed, apices flattened or slightly convex, level with surface of areoles or slightly emergent; exciple: subglobose, 0.15-0.22 mm wide, dark; involucrellum: contiguous with exciple, covering at least the upper two-thirds of the perithecium, mostly extending to exciple-base level and ± incurved beneath, laterally c. 30 µm thick; periphyses c. 20 µm long, simple asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 11-15(-16) x 5-7 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: epilithic, on siliceous rocks at elevations from 50-1250 m World distribution: Europe and North America Sonoran distribution: southern Arizona (Cochise, Pima, and Santa Cruz Counties), Baja California, Baja California Sur, California, Chihuahua, and Sonora. Notes: Contrary to the European samples, the North American specimens of Verrucaria lecideoides are from siliceous rocks. The species is often confused or synonymized with Verrucaria beltraminiana which differs in having both larger perithecia and spores.