This impressive volume, the first hardback I have seen in this series, represents a huge effort involving 17 contributors, mainly based in North America and including three from Mexico.

Mexico is an extraordinarily diverse country, as anyone who has driven on the same day from humid forests near the coast to the lower slopes of the central mountains that rise to some 7500m (18700ft) will be well aware. This lichen family is well represented here by 39 genera and some 450 species, around 20% of the species in the family known worldwide.

Three introductory chapters set the scene. The first is a superb synopsis of the geology, topography, climate and vegetation types that will be of value to any lichenologist visiting the country, whatever their speciality. It might come as a surprise to many that the temperature range in a single locality can be from −16°C to 48°C. The second analyzes metacommunities by innovative phylogenetic methods, revealing temperate forests as the source of most diversity in the family, and the humid mountains and tropical forests as the least. The third provides an overview of current generic concepts in Parmeliaceae, now settling down as a result of intensive molecular studies over the last 15 years, and includes a key to the treated genera, something especially welcome as this has not been provided in recent phylogenetic overviews in specialist journals.

Each genus is treated as a separate chapter with clear author attributions so they can be cited separately. The format has evidently been rigorously standardized and bears the signs of being streamlined by the third editor, Tom Nash, well known for the superb job he made of the Sonoran Desert lichen volumes (Nash et al., Lichen Flora of the Greater Sonoran Desert Region, 2002–2007, 3 vols, Tempe: Lichens Unlimited). After an abstract and background notes on each genus, there is a key to the treated species. Each species entry also includes the places of publication of accepted names and selected synonyms, followed by references to published illustrations, a full description, information on extrolites and distribution, sometimes followed by notes and always with full details of specimens examined (for the more common species this can cover several pages in small type). References cited are conveniently collected together at the end of the volume where they occupy no less than 30 pages. Sadly there is no index; one organized by species epithet would have been much appreciated by those unsure of which genus any particular species was now placed in.

The most species-rich genera proved to be Parmotrema (85 species), Hypotrachyna (80), Xanthoparmelia (74) and Usnea (66). There are few taxonomic changes. I was pleased to see that the raising of Canoparmelia subgen. Crespoa to generic rank was not accepted, nor was Gowardia recognized as distinct from Alectoria. I was, however, sad to see Phacopsis still used for Nesolechia oxyspora despite the published molecular evidence to the contrary. Many new species found during work towards this monograph had already been published elsewhere, and just eight are newly described here, in Alectoria (2), Hypotrachyna (1), Parmotrema (2), Pseudevernia (2) and Tuckermanella (1). All are accompanied by fine colour photographs. Sadly, no molecular data to support these new taxa are provided, and in several cases the new species were largely based on extrolite differences, something that might prove to be unwise as it is now clear that different chemotypes can occur in a single species in this family. A few new combinations are also presented.

The decision not to include photographs of all but the newly described species and a few exemplar ones in the introductory chapters is understandable because of the large number involved. The citation of illustrations is a good second best, and especially informative are a series of scanning electron micrographs (SEMs) illustrating the development of the different categories of dual asexual propagules in Punctelia, with a key to their separation.

This enormous undertaking was made possible through funding provided by the US National Science Foundation, with the University of Arizona as the lead. This not only enabled numerous field excursions to be made which provided a satisfactory coverage of such a vast area and a way of involving Mexican researchers, but also facilitated the examination of numerous pertinent collections in various institutions around the world; 34 institutional plus several private collections are acknowledged. This impressive volume is an excellent example of what can be achieved if adequate funding is provided to a highly motivated and talented team. It is a ‘must’ for the Parmeliaceae community worldwide, as well as for ecologists and lichenologists working in the country. Mexican lichenologists would benefit from a set of the keys being made available in Spanish, something I would expect already to be in hand. The editors and contributors are to be congratulated on realizing such a vision.