This richly illustrated booklet in field-guide format presents 225 lichen species found on St. Helena. This small (122 km2) remote (2000km to nearest major land mass) volcanic island is situated in the Southern Mid-Atlantic, even today reachable only by boat after a trip lasting several days, and it is famous because Napoleon spent his last years there. Its maritime climate favours the growth of lichens, which are a conspicuous component of the vegetation, in particular on the scarcely vegetated rocky slopes at lower elevations. No less than 9 endemic lichen species are known so far, quite unusual for lichens, which normally have wide ranges.
The booklet treats all species presently known from the island, and 223 species are illustrated by one or more full colour photographs. Most pages are used for very concise descriptions of the genera and species. These are arranged partly alphabetically, partly after morphological similarities. This reflects the key to the genera, which consists of separate keys for five morphological groups (fruticose, foliose, squamulose, placodioid and crustose). The genera are sorted into these five groups, and within each group they are ordered alphabetically. Each genus description is followed by paragraphs on the species found on St Helena and their distinguishing features, on the differentiation between similar genera found on the island, and on world distribution and ecology. In addition, each species photograph is accompanied by one or two lines indicating its characteristics and habitat. The photographs are on the opposite page to the species text. The descriptive part is preceded by a general introduction to lichens, notes on the significance of St Helena for lichens, on the lichen habitats on St Helena, and on how to identify lichens. The last 7 pages bring a glossary, illustrations of key characters, 10 titles for further reading, and an index to the genera.
The booklet has the layout of a field guide and brings illustrations of superficially similar taxa together, which facilitates identification. The morphological groups are easily found by a different colour at the upper page margin, and each habitat photograph legend lists the principal characters of the species shown. The photographs focus on details relevant for identification. Unlike most field guides, which include only a selection of conspicuous species, this booklet treats all the known species of the island.
The overall quality of the photographs is high and they include many pictures of rarely illustrated species. Some pictures are more appealing than others but the trained eye will easily detect the details significant for recognition of the species. In only two cases is the colour unnatural and misleading: The thallus of p. 33 fig. 1 looks yellow like a Relicina species, and not pale grey like a Bulbothrix, and Fig. 7 on p. 73 shows red apothecia (yellow to orange in the accompanying text). Without a standard identification work for lichens from places as small as St Helena, their identification requires consultation of a very extensive literature and study of specimens from various herbaria by somebody with a wide experience with tropical and subtropical lichens. The St Helena Nature Conservation Group was fortunate to have one of the most experienced people in the world to do the identification, but also the collecting, which equally requires much experience. However, the reader should keep in mind that taxonomic knowledge of many extra-European lichen groups is still very incomplete and that ongoing research is changing species and genus concepts continuously. Therefore one cannot expect final identifications for all species occurring in a place like St Helena as one might, for example, with a British island. In particular in genera like Caloplaca and Pertusaria accounts are sometimes provisional, and future revisions are likely to bring name changes, and perhaps more endemism. Taking this into account, the author is to be praised for producing such a detailed treatment of the lichen mycota of St Helena.
Summarizing, this book is a remarkable achievement well worth a place in every lichenological library, especially for those interested in lichen biogeography. It will enable anybody who has the chance to visit St. Helena to name the encountered lichens quickly. For lichens from outside the island the colour photographs of rarely illustrated taxa can be of significant help with the recognition of tropical taxa.
