Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Thallus: areolate or subsquamulose or irregularly divided, up to 0.2 mm thick (sterile parts) or up to 0.4 mm (fertile parts), lacking a prothallus areoles: plane to slightly convex, roundish angular in outline, with rather broad fissures, areoles 0.3-0.7 mm wide when well developed but sometimes irregularly divided into smaller fragments thus forming a verruculose thallus; base of areoles or verrucules slightly constricted and elongated (2-3 times as thick as areole) to form a stipe-like organ that fixes the thallus units within the substrate and leaves a cavity when the areole is removed or falls out surface: pale gray, dull, minutely wrinkled, epruinose anatomy: with an indistinct upper cortex formed by a row of brown cells 3-6 µm in diam., with an amorphous, hyaline epinecral layer 10-60 µm thick; algal layer: subparaplectenchymatous, filling almost the whole thallus, with algal cells 6-12 µm wide; the lowermost zone of thallus: partly filamentous, with tiny substrate particles, developing perpendicular, hyaline hyphae that form the stipe-like organs that penetrate the substrate Perithecia: immersed with only the tip exposed; exciple: 0.2-0.3 mm wide, (sub)globose, c. 15 µm thick, apically slightly thicker, colorless except around ostiole when young, later blackening all around; involucrellum: lacking; periphyses 20-25 µm long, 2-2.5 µm thick asci: clavate, 8-spored ascospores: hyaline, simple, broadly ellipsoid to subglobose, 9-12 x 7-9(-10) µm Pycnidia: 50-80 µm in diam., with irregularly sunken mouth conidia: bacilliform, 6-7.5 x 1 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on soil and soft rock surfaces over limestone as well as sandstone World distribution: Europe and southwestern North America Sonoran distribution: Baja California and Arizona. Notes: Verrucaria bernardinensis is very similar but has pruinose areoles and longer conidia and is lichenicolous.