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

Thallus: rarely indistinct (endolithic) to usually distinct, rimose to irregularly areolate; prothallus: indiscernible to distinct, black areoles: flat, irregular, 0.1-0.4(-1) mm thick surface: white to pale gray or sometimes red to rusty red or ochre (due to incrustations of iron-oxides), smooth to rough, esorediate cortex: 10-30 µm thick medulla: white, I+ intensely violet; algal layer: 60-90 µm thick Apothecia: black, marginated, usually with a constricted base, up to 1.2(-3) mm in diam. disc: black, flat to moderately convex, dull, epruinose or (rarely) indistinctly pruinose margin: black, persistent, dull to shiny exciple: black-brown peripherally, with an 30-80(-120) µm wide unpigmented interior epihymenium: greenish black to brownish black, 10-15 µm thick hymenium: hyaline, 4575 µm tall, I+ blue; paraphyses: usually unbranched and rarely anastomosing, with swollen apical cells, 3.5-5 µm in diam. subhymenium: unpigmented or faintly green, 1065 µm thick hypothecium: unpigmented, pale ochre to medium brown asci: clavate, Lecidea-type, 40-65 x 12-16 µm, 8-spored ascospores: hyaline, simple, ellipsoid, mean values: 8.9-14.5 x 4.6-7.3 µm, length-width-index: 1.5-2.9 Pycnidia: immersed conidia: cylindrical, +straight, (11.5-)12-16(-22) x 1-1.3 µm [studied in 5 specimens] Spot tests: cortex and medulla K- or K+ yellow or K+ red, C-, KC-, P- or P+ yellow or P+ yellow-orange Secondary metabolites: stictic acid syndrome (var. lapicida) or norstictic acid syndrome (var. pantherina Ach.). Substrate and ecology: in open to exposed, alpine habitats on granites, schist and other acidic rocks, in regions with a humid climate World distribution: bipolar and extending into the tropics in alpine areas (e.g. Andes of Venezuela) Sonoran distribution: unknown but expected at the highest-most elevations (e.g.) San Francisco Peaks. Notes: In cold and humid areas Lecidea lapicida is a common and very widespread species. It is characterized by its I+ violet medulla, its medium sized ascospores, its usually pale (unpigmented to medium brown) hypothecium and its chemistry. Its thallus varies greatly: from cryptothalline to well developed.  Rusty colored specimens are rather common.  The epitheton is Latin and means "stonecutter".