Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Life form: lichenized Thallus: pale, inconspicuous endophleoedic photobiont: Trentepohlia Ascomata: richly branched, with irregularly sinuous branches, branches often cracked into polygonal units, slightly emerged, 50-90 µm tall disc: dark brown, wax-like in appearance, lacking pruina; peripheric hyphal structures and subhymenium with refractive crystals epihymenium: hyaline to pale brown, 10-20 µm thick; paraphysoidal tips c. 2.5 µm wide hymenium: hyaline, 40-45 µm tall, paraphysoids branched and anastomosed, to 2 µm wide; subhymenium: hyaline, 15-25 µm thick asci: broadly clavate, 35-40 x 15-22 µm, 8 spored ascospores: hyaline, 3-4 septate, slightly constricted at uppermost septum, obovoid, macrocephalic, 13-19 x 5-7 µm, smooth Pycnidia: not observed Chemical reactions: ascomatal gels I+ blue, KI+ blue; asci with KI+ blue tube-like ring-structure. Substrate and ecology: on smooth bark World distribution: North America Sonoran distribution: southern California (Catalina Island). Notes: Arthonia pyrrhuliza was sometimes confused with Arthonia pyrrhula (now Coniarthonia pyrrhula), a species with crimson pigments throughout its hymenia. The specimen from the Sonoran area differs from typical A. pyrrhuliza by the fine crystals that are found in the hymenium.