Wilson R.S., Ruse L.P. 2006. - A guide to the identification of genera of chironomid pupal exuviae occurring in Britain and Ireland (including common genera from Northern Europe) and their use in monitoring lotic and lentic freshwaters. FBA Special Publication N°13, D.W. Sutcliffe (Ed.), August 2005, Freshwater Biological Association, Ambleside UK : 176 pp. ISBN 0-0900386-73-8, ISSN 1747-1958 £ 20.00 - Review printed in Internat. Rev. Hydrobiol., 91(2) : 195.

This Special Publication N°13 of the Freshwater Biological Association, is a revision of "A practical key to the genera of pupal exuviae of the British Chironomidae" published by Dr. Ronald S. Wilson in 1996. Part-sponsored by the UK Environmental Agency, this new edition aims to provide basics for non-specialists to use chironomid pupal exuviae in assessing and monitoring freshwater habitats.

The guide comprises two distinct although complementary parts. The main part comprises a set of well illustrated multiple choice keys for a facilitated identification of pupal skins of genera and selected species of Chironomidae from British islands (Chapters 6 to 15). Those keys go along with an extensive description of pupal exuviae morphology (Chapter 4) completed by an easily comprehensive glossary of the terms used in the keys (Chapter 5). The authors also included a taxonomical and ecological-orientated introduction to the Family Chironomidae (Chapters 1 and 3).

In the second part the Chironomid Pupal Exuvial Technique (CPET) is presented and discussed (Chapter 2 and 16). CPET is an assessment method based on tolerance abilities to organic stress of chironomid genera and species, which have been developed by the authors to survey the organic enrichment of a wide range of fast flowing and stagnant freshwater habitats. CPET was already introduced in the Wilson´s earlier guide. Although the authors tried, in this new edition, to put more emphasis on the CPET, they actually failed to do so. Despite 10 years of implementation, no significant new input is given to further illustrate and critically discuss the method. Moreover, the sub-chapter entitled "data analysis" appears to be out of scope by reviewing current multivariate statistical methods available to analyze large sets of faunistic data. Here, I would have expected to find an illustrated 'real world case study' on how to operate the CPET in order to assess changes in freshwater organic content. The two additional plates of colored pictures illustrating how to locate and collect flotsam in various water-bodies are indeed helpful.

Clearly, the value of this new edition resides in the updated taxonomical revision of the 145 genera presented with additional entries for about 100 species recorded in Britain and Ireland. Most of the free-hand drawings have been improved and additional drawings efficiently help the taxonomic identification. There is no doubt that this guide provides a comprehensive package serving freshwater biomonitoring purposes. It is additionally not restricted to British freshwaters as most of the genus and species presented are commonly recorded in the palaearctic region. It entirely fulfills its aim to be understandable and easy to use for a large and non-specialist public.

Despite its weakness in not thoroughly illustrating and promoting the CPET, this new edition is welcome as such a revision was highly needed.

Xavier-François GARCIA