Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Life habit: lichenized Thallus: foliose, continuous and rosette-forming or rarely fragmentary, 3-10 cm wide, loosely adnate, lobate lobes: irregular, broadly elongate, marginally entire or indented, with or without lobules; apices: usually subrotund to rotund, often ascending, eciliate upper surface: gray brown to brown or yellow- green (non-Sonoran species), pruinose or not, with or without soredia or isidia upper cortex: pseudoparenchymatous, 10-30 µm thick cortex: pseudoparenchymatous, 20-40 µm thick medulla: white or yellow, with loose hyphae, 40-260 µm thick photobionts: primary one either a chlorococcoid alga (Coccomyxa) or cyanobacterium (Nostoc); secondary photobiont of Nostoc present in internal cephalodia in chlorococcoid species lower surface: pale brownish to brown or yellow-green, glabrous, pubescent or tomentose; rhizinae, cyphellae and pseudocyphellae absent Ascomata: apothecial, sessile or immersed on the lower surface at tips of lobes, orbicular or reniform, cup-shaped, sessile, margin: prominent with thalloid rim; disc: pale brown or red-brown to dark brown; exciple: hyaline or light brown, 20-30 µm thick, epithecium: brown or brownish yellow; hymenium: colorless, 60-90 µm tall; paraphyses: unbranched; hypothecium: hyaline asci: simplified "Peltigera"-type, c. 8-spored ascospores: subfusiform to fusiform, pale brown, 3-septate, thin walled, 10-18 x 6-10 µm Conidiomata: pycnidial, marginal, semi-immersed, punctiform, ostiole dark conidia: bacilliform, 9-16 x 1 µm Secondary metabolites: hopane triterpenoids, depsides and pigments Geography: cosmopolitan, polar, boreal-montane and coastal, temperate forests; both Northern and Southern Hemispheres Substrate: commonly on bark, acidic rock or soil. Notes: It is similar chemically and morphologically to Peltigera but lacks the veins found on the lower surface of the latter genus. The presence of a lower cortex in Nephroma also distinguishes it from Peltigera. Among all foliose genera in this region, the presence of apothecia on the lower surface of the lobes in Nephroma is unique.