Thallus: fruticose, pendent, main branches flattened, usually 5-15 cm long lobe surface: grayish, often uneven with ridges and wrinkles soredia: farinose, in maculiform soralia which may often fuse to cover much of the lobe surface medulla: white but brown in the holdfast zone, usually with a yellowish tinge Ascomata: not seen 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 from California to south-central Chile, and possibly Carribean and pantropical Sonoran distribution: extending from southern California south to the tip of Baja California along the Pacific coast and also occurring in southern parts of Sonora and adjacent Sinaloa. Notes: Roccella peruensis is characterized by its sterile, sorediate thallus. Roccella peruensis feels somewhat softer and less robust than R. decipiens, probably due to the presence of soralia. The name and R. babingtonii Mont. (Montagne 1852) has been frequently used for this taxon in California and Mexico. Roccella babingtonii, however, was described by Montagne as having apothecia only; soredia were not mentioned by him. Thus, Montagne's description cannot be applied to the sterile, sorediate taxon R. peruensis (Krempelh.) Darb. The description of R. babingtonii Mont. better fits to the fertile R. decipiens Darb. above and may in fact be the oldest name for that taxon. Morphological, chemical and molecular investigations (Myllys et al., 1999) indicate that Roccella peruensis may be the sterile counterpart in a species pair relationship with the fertile R. decipiens (above). Thus, the name R. peruensis may be subject to change when the the genus Roccella is revised.