The lichen genus Physcia in Central and South America

Thirty‐four species of the lichen genus Physcia (s. str.) in Central and South America are defined. Morphology, anatomy, chemistry, distribution, habitat, relation to other taxa and some evolutionary trends are discussed. A key to the species is presented. Eleven species are described as new; P. cinerea, P. convexella, P. coronifera, P. decorticata, P. kalbii, P. lobulata, P. lopezii, P. manuelii, P. rolfii, P. sinuosa , and P. tenuis. P. nubila is a new name for Heterodermia desertorum .