Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: fruticose, pendent, main branches flattened, usually 5-20 cm long lobe surface: grayish to grayish-brown, often uneven with ridges and wrinkles; without soredia medulla: white but brown in the holdfast zone, usually with a yellowish tinge Ascomata: usually present; circular in outline but often with undulating margin, sessile with constricted base, rarely immersed, up to 2.5 mm diam.; hymenium: 70-90 µm; paraphysoids: sparsely branched, hyaline, <2 µm diam. asci: clavate, 60-85 x 12-14 µm, 8-spored ascospores: fusiform, curved, hyaline, 3-septate, 22-27 x 5-6 µm; walls: smooth Spot tests: cortex K+ more or less yellowish red (sometimes inconspicuous), C+ red, KC+ red, P-; medulla K-, C-, KC-, P- Secondary metabolites: erythrin and lecanoric acid. Substrate and ecology: grows near the sea on any suitable substrate, such as the vertical rocks and cliffs and on the trunks, branches and twigs of various trees and shrubs World distribution: uncertain, but probably extending from California to south central Chile, and possibly also the Carribean and pantropical Sonoran distribution: along the western coast of California from San Francisco south to the tip of Baja California along the Pacific coast. It is also present on the Mexican mainland in the southern part of Sonora and adjacent Sinaloa. Notes: Roccella decipiens is characterized by the fertile, non-sorediate thallus and feels somewhat stiffer and more robust than R. peruensis probably due to the lack of soralia that weaken the cortex. The name R. fimbriata (Darbishire 1935) has been frequently utilized for this taxon in California and Mexico (e.g. Hale 1979). However, R. decipiens (Darbishire, 1898) is an older name and thus take precedence over R. fimbriata (also see Notes under R. peruensis below). Roccella decipiens was described from southern California by Darbishire (1898) as being a constantly fertile species without soralia. Furthermore, morphological, chemical and molecular investigations (Myllys et al., 1999) indicate that Roccella decipiens may be the fertile counterpart in a species pair relationship with the sorediate Roccella peruensis (below). Thus the name Roccella decipiens may be subject to change when the the genus Roccella is revised.