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

Thallus: crustose, continuous or verrucose-areolate; prothallus: not visible, or white areoles: flat or verrucose or verruculose, thin, opaque, ecorticate surface: yellowish white to yellowish gray or whitish gray to gray, smooth or rough, epruinose, with an indistinct margin, esorediate Apothecia: sessile or adnate, 0.3-1.5 mm in diam., lecanorine disc: red-brown or brown or dark brown to blackish brown, plane, epruinose margin: concolorous with thallus, thin or thick, persistent, even or prominent, not flexuose, smooth, entire or verrucose or verruculose, without a parathecial ring amphithecium: present, with numerous algal cells, with large crystals insoluble in K, corticate; cortex: distinct, basally thickened, gelatinous or interspersed, hyaline, (10-)15-20(-25) µm thick laterally, 25-65 µm thick basally parathecium: hyaline, containing crystals soluble in K epihymenium: with pigment dissolving in K, with fine crystals dissolving in K, red-brown to orange-brown hymenium: hyaline, clear; tips of paraphyses: slightly thickened (up to 3.5 µm wide) apically, not pigmented; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid or broadly ellipsoid, (9-)9.5-13(-16) x (6.5-)7-9(-10.5) µm; wall: around 1 µm thick Pycnidia: immersed, cerebriform; conidiophores: type II sensu Vobis conidia: filiform, (11-)14-17(-19) µm long Spot tests: K+ yellow, C-, KC-, P+ orange to red or P- Secondary metabolites: atranorin (major), chloroatranorin (minor), confumarprotocetraric acid (trace or absent), fumarprotocetraric acid (major or absent), roccellic acid (major or absent). distribution: Arizona, and southern California. Notes: Lecanora pulicaris is the only species of the L. subfusca-group in the Sonoran desert region that contains fumarprotocetraric acid and thus easily identified. However, some spcimens may lack this substance and only contain traces of the depsidone that produce a negative P reaction. Such chemotypes are difficult to separate from the similar L. circumborealis and L. hybocarpa. The most reliable characters to distinguish L. pulicaris and L circumborealis, are the basal thickness of the amphithecial cortex and the size of the ascospores. L. circumborealis has larger ascospores and a thicker cortex at the base (Brodo 1984).