Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: crustose, mostly smooth to verruculose, +rimose, 0.3-0.5 mm thick surface: rather variable in color, white, cream-colored, pale gray, or greenish gray, dull, esorediate Apothecia: immersed, aspicilioid or sessile, often dense, 0.3-1.5 mm in diam. disc: scarlet red to dark cinnabar red, often confluent, epruinose margin: concolorous with thallus, persistent, either distinctly developed, smooth to slightly crenulate or very narrow in immersed apothecia exciple: red, thin epihymenium: scarlet to dark orange-red (K+ red or magenta to purple) hymenium: hyaline, 70-110 µm tall; paraphyses: strongly branched and reticulate, gelatinous, with only slightly swollen apices; hypothecium: hyaline asci: clavate, 8-spored ascospores: hyaline, transversely 6-7 septate, straight or sigmoid-curved, 30-50(-55) x 3.5-5 µm Pycnidia: immersed conidia: filiform, curved, 16-20 x 1 µm Spot tests: thallus K+ yellow, C-, KC-, P- Secondary metabolites: atranorin, sphaerophorin, isosphaeric acid, and russulone. Substrate and ecology: on bark of a wide variety of trees or shrubs, with broad ecological amplitude, from arid to humid areas World distribution: pantropic, widely distributed, Africa, Asia, Australasia, Oceania, South America, the Caribbean and southern parts of North America Sonoran distribution: Baja California Sur, Sonora and Sinaloa at 10-150 m. Notes: Though very variable, Haematomma persoonii is characterized by its mostly smooth to verruculose, whitish gray to yellow-gray thallus, immersed to sessile apothecia with scarlet to cinnabar red discs, 6-7-septate spores, and the presence of sphaerophorin and/or isosphaeric acid, in addition to russulone.