Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Thallus: areolate to subsquamulose, 0.15-0.20 mm thick, without a prothallus areoles: angular or irregular roundish to slightly lobed, plane to slightly convex, 0.3-0.8 mm wide, separate or in small groups or forming more extensive patches, partly basally somewhat constricted surface: brown, smooth, dull or slightly glossy anatomy: upper cortex: paraplectenchymatous, composed of polygonal cells 3-7 µm in diam., 15-25 µm thick, hyaline, overlain by an amorphous epinecral layer 10-15 µm thick formed by empty flat cells; algal layer: concentrated in upper part of the thallus or filling most of thallus thickness, with algal cells 5-12(-15) µm wide; mycobiont portion: paraplectenchymatous, cells 4-8 µm diam., alga-free medulla subparaplectenchymatous, colorless, inspersed with crystals, in marginal parts free from the substrate a thin lower cortex of 2-3 dense rows of cells may develop Perithecia: entirely immersed, several within each areole; exciple: sub-globose or broadly pyriform, 0.20-0.25 mm wide, black all around, c. 20 µm thick, apically slightly thicker; involucrellum: lacking ; periphyses 15-20 µm long asci: clavate, 40-50 x 15-20 µm, 8-spored ascospores: hyaline, simple, broadly ellipsoid, 12-15 x 7-8.5 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: epilithic, on non-calcareous or superficially slightly calciferous rocks World distribution: southwestern North America Sonoran distribution: Arizona and Baja California Sur. Notes: The species is externally similar to Verrucaria compacta from which it differs by thinner and smaller thalli, and smaller perithecia with a black exciple. Verrucaria rupicola has narrower ascospores and is calcicolous.