Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: squamulose-umbilicate, 1.5-5 mm wide, surface: brownish olive, basal parts sometimes lighter, smooth, sometimes slightly pruinose, especially around the apothecia, margin: slightly incised, sometimes downcurved, sometimes distinctly placodioid lower surface: attached to the substrate by rhizohyphae Apothecia: immersed to semi-immersed, zeorine, up to 10 per squamule, 0.25-0.75 mm wide; disc: slightly depressed to flat, brownish, smooth to rigid, open, with persisting thalline margin; exciple: distinct, up to 20 µm wide, hyaline, composed of strongly gelatinized hyphae; epihymenium: yellowish-brown; hymenium: hyaline, amyloid, divided by bands of sterile hyphae, 95-140 µm high; paraphyses: distinctly septate, sparingly branched and anastomosing, straight, apical cells thickened, 2.5-5 µm wide asci: 8-spored ascospores: simple, hyaline, ellipsoid, rarely well developed, 10-14 µm x 4-8 µm; walls: thin Pycnidia: immersed, globose to broadly pyriform, 0.1 mm wide; pycnidial wall: convoluted with age conidia: cylindrical, 2.5 x 1 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on thin soil crusts over calcareous, rarely volcanic rocks on rocky slopes; coastal to montane World distribution: SW North America Sonoran distribution: Baja California Sur, Baja California and Sonora. Notes: In some respects the species resembles Gloeoheppia turgida, a species distinguished from P. heppioides by its inflated thallus with large internal air-spaces.