This publication presents a detailed taxonomic treatment of 71 species in two related lichen genera of Ramalinaceae found along the Pacific coat of North America in which 53 new species of Niebla and Vermilacinia are described. Many of the species are conspicuous among the landscape vegetation of the Pacific coastal deserts, constituting 70% or more of the ground cover in some areas, but also growing luxuriantly on shrubs and trees. Color photographs are presented for most species as seen in their natural habitat in Baja California, Mexico. The author has been studying and photographing these lichens for more than 10 years. The treatment includes an introduction on the history of the generic classification, climate, vegetation, and phytogeography for the Californian regions, followed by a discussion of characters employed in taxonomic keys and descriptions. Two types of keys to species are presented: (1) one emphasizes morphological characters, which is accompanied by many illustrations, and (2) a second is weighted on chemical characters. This is followed by detailed description of each species. 129 black and white photographs of representative specimens are shown; the type is usually shown first, and for some species, particularly in Niebla, as many as eight photos are shown to help the user grasp the morphological characters of the species. Additionally, maps of the California regions are presented at the beginning, and chemical structures of key compounds are shown at the end.

This publication will be of particular interest to naturalists who travel to Baja California and to the Channel Islands of California as well as to lichenologists, educators and researchers interested in Mexico’s vegetation.