Reproductive Biology and Phylogeny of Annelida * Volume edited by Greg Rouse and Fredrik Pleijel Series edited by Barrie G.M. Jamieson.

This is the fourth book in the series and was published in 2006, others have dealt with Urodela, Anura, and Chondrichthyes. Rouse and Pleijel have assembled a range of authors to either write chapters on their own or with them, and in addition Rouse and Pleijel have written chapters on their own. The first chapter by Rouse and Pleijel introduces Annelid phylogeny and systematics, and they summarize the recent revisions of the group and the now generally accepted view that Echuira, Pogonophora, and the Clitellata are really within the Polychaeta, although to date we still have no robust support for any sister-group relationship with a particular polychaete group. As in Rouse and Pleijel (2001) they use the informal names “polychaetes” and “oligochaetes” and avoid the terms Polychaeta and Oligochaeta, and indicate that soon either the name Polychaeta or Annelida will be redundant. This summary of the current state of the systematics of annelids will be welcome to invertebrate biologists as to what names they should be using and which groups are included and which are not. Basically this instability is the result of a lot of ongoing studies using molecular and morphological data which are beginning to unravel this fascinating group, although we still lack any clear idea as to the root position of annelids although the jury has finally accepted that annelids are closer to the molluscs than to the arthropods with which they have historically been linked. While Rouse and Pleijel are confident that this will be resolved shortly, I suspect the jury will be out for some time as we are still resolving relationships within the major clades. Trying to obtain congruence between morphological and molecular data, has been difficult and not helped by the limited fossil record available for these groups. The book is divided into two sections, the first dealing with general reproduction and phylogeny and the second with selected groups of annelids, and it is to be regretted that two large clades of polychaetes, the Euncida and the Terebelliformia, are not included and similarly for the Echiura and Siboglinidae, although recent reviews have been published of the latter two groups although not specifically dealing with reproduction. Given the fact that interpreting the phylogeny of this group is such an active and dynamic area of research and the usefulness of using reproductive characters to resolve this, it is slightly surprising that some of the chapters appear to provide no additional data and in some cases the references seem to end around 2000–2001. Other chapters provide a very useful update and synthesis of historical and recent data. I particularly enjoyed the chapter on “Early Annelid Development, a Molecular Perspective” which is a great summary of this rapidly expanding field and many will find this an extremely timely synthesis. I was surprised that the chapter on “Sexual Strategies and Mating Systems” provided no reference to mass spawning which is undertaken by a large percentage of polychaetes and as there have been recent reviews of this, these could have been included together with the vast amount of data on the endocrine control of reproduction. The chapter by Rouse on Annelid larval morphology is also a very welcome synthesis of what is known and provides a useful table listing most of the studies for each of the groups which will be useful to people undertaking phylogenetic studies, but also it highlights the gaps in our knowledge. The chapter on “Larval Ecology of the Annelids” summarized the experimental studies that have been undertaken by the authors, and it seems as if Hydroides elegans is the only experimental animal used; it would have provided a more useful review if a broader perspective had been undertaken. As a polychaete worker, I found the synthetic chapters on the non-leech Clitellata and the Hirudinida interesting and they will be useful as traditionally we have almost ignored these groups, but now all the evidence indicates that they are nested within the polychaetes and we do need to consider them when undertaking revisions of the group. This book presents, for the first time, comprehensive accounts of the reproductive biology and phylogeny of major clades of polychaetes and highlights the amazing diversity even within a clade, which, perhaps, explains why the resolution of the overall group has proved such a problem as there appears to have been so much radiation within a clade. This is highlighted in the last chapter on the problematic annelid groups, mainly small species that are often highly adapted to living interstitially and have lost many characters making their placement difficult. Detailed morphological studies using SEM and TEM together with molecular studies are beginning to unravel their origins and relationships. So the publication of this book is timely given the interest worldwide in trying to resolve the relationships within this group, the largest invertebrate group for which we still have an incomplete picture. I recommend this book to all researchers and students interested in annelids and at US$135 it is a very reasonably priced given the large number of illustrations and colored plates and its sturdy binding. The authors and publishers should be congratulated on this. Some more careful editing could have been undertaken; while the terms chaetae and chaetiger are used most often, there are places where the terms setae and setiger are used. Some references are lacking either a journal or title but, given the large number of authors involved, this is not surprising. In addition, some consistency in figures would have been useful; most are great but they do vary in format and labeling.

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