Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Life habit: lichenized Thallus: grayish white, finely fissured-areolate areoles: in section up tp 0.6 mm thick, with a distinctly thick medulla (I+ blue) filled with numerous granules (K+ soluble) photobiont: trentepohlioid Ascomata: irregularly rounded, 0.5-1.8 mm in diam., or slightly elongated and up to 2 x 0.8 mm, immersed in thallus warts, isolated, disc: dark brown to black, ±convex, distinctly white pruinose epihymenium: reddish brown to dark brown, 10-20 µm thick; tips: enlargened up to 5 µm wide hymenium: hyaline, 70-80 µm tall; paraphysoids: branched and anastomosing, 1.5 µm thick; subhymenium: hyaline to light brown, 50-100 µm thick asci: clavate, 40-50 x 18-23 µm ascospores: hyaline, 2(-3) septate, the middle cell distinctly elongated and upper cell wider, oblong-ovoid, 14-17 x 6-7 µm, without or with poorly developed epispore Pycnidia: immersed, unilocular, 350 x 250 µm conidia: filiform, curved, 13-20 x 1 µm Chemical reactions: thallus K+ yellow, C-, P+ orange (yellow); ascomatal gels I+ blue turning red, KI+ blue; ascus tholus KI- Secondary metabolite: psoromic acid. Substrate and ecology: on vertical rocks to underhangs in habitats with at least some fog influence World and Sonoran distribution: Baja California and Baja California Sur. Notes: Arthonia verrucosa is similar to A. gerhardii, which is a more robust species that has confluentic acid as well as psoromic acid. The latter species occurs in more strongly maritime habitats near the Pacific Ocean.