Thallus: cracked-areolate to subsquamulose, 0.25-0.40 mm thick, with cracks of varying width, partly with a dark fimbriate prothallus visible areoles: ±round-angular to rounded in outline, or subcrenulate, plane to slightly convex, sterile areoles 0.2-0.5 mm, fertile ones 0.5-0.8 mm wide, often slightly constricted at base, separated by thin and subacute (in young parts) or broader obtuse cracks (in older parts of the thallus), marginal areoles smaller and thinner surface: brownish gray to brown, dull, thinly sulcate-wrinkled anatomy: upper cortex not discernible; algal layer paraplectenchymatous, 50-100 µm thick, algal cells 5-10 µm in diam.; alga-free medulla: composed of looser texture with substrate particles and crystals, patchily brown Perithecia: 1-3 per areole, immersed to slightly emergent; exciple: broadly pyriform to subglobose, 0.25-0.45 mm wide, colorless to brown, 15-25 µm thick; involucrellum: appressed to the exciple, extending down to the lower part of the perithecium, 40-50 µm thick, at base often slightly thinning or dissoluting, sometimes shortly incurved beneath the exciple; periphyses: upper ones 20-30 µm long and simple, lower ones 35-45 µm long and slightly branched asci: clavate, 90-105 x 27-40 µm, 8-spored ascospores: hyaline, simple, broadly ellipsoid, 22-30 x (11-)12-15 µm Pycnidia: unknown Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: epilithic, on ±calciferous rocks (limestone, conglomerate, shale) World and Sonoran distribution: locally common in central Arizona (Maricopa, Pinal, and Yavapai Counties). Notes: The species is a distinctive species with furrowed-verrucose areoles and largely immersed perithecia with apices seen in surface view shaped like ink blots due to the furrows radiating from the perithecia. The color of the thallus may be brown or pale. Irregularly shaped perithecial apices also occur in Verrucaria subdivisa, but in this latter species the thallus is pruinose and rather even, the involucrellum is thicker, and the spores are narrower. Verrucaria murorum may also bear some external similarities, but has a thicker involucrellum and even larger spores.