Fishes: A Guide to Their Diversity

Fishes, with approximately 33,000 currently known valid species, is a non-monophyletic group composed of five or six extant lineages of craniates: the Myxiniformes and Petromyzontiformes (hagfishes and lampreys), often combined as the Cyclostomata (e.g. Heimberg et al. 2010), the Chondrichthyes (sharks, rays and chimaeras), the Actinopterygii (ray-finned fishes), Actinistia (coelacanths) and the Dipnoi (lungfishes). The vast array of forms and adaptations of this highly diverse assemblage has fascinated humankind since time immemorial. ‘El Gran Pez Negro’ (the Great Black Fish), for instance, is a remarkable 1.6 m long, 20,000-year-old painting in the ‘La Pileta Cave’ (Spain) that clearly depicts a member of the Pleuronectiformes, probably the European flounder Platichthys flesus (Linnaeus, 1758) (Citerne & Chanet 2005; Bicho et al. 2007). Early in the Renaissance, Pierre Belon (‘L'Histoire Naturelle des Estranges Poissons Marins’, 1551) and Guillaume Rondelet (‘Libri de Piscibus Marinis’, 1554) established the basic format followed by most, if not all, books devoted to promoting fish diversity and identification. Fishes: A Guide to Their Diversity by Philip A. Hastings, H. J. Walker Jr and Grantly R. Galland elegantly dwells amidst this historical tradition.

The guide is divided into three parts. The Introduction briefly describes the aims and scopes of the book. Basic information on fish diversity and systematics, mostly adequate for introductory courses or non-experts, is presented. The classification schemes adopted are briefly described. At the upper levels of the taxonomic hierarchy, they basically follow Wiley and Johnson's (2010) recent review of the Teleostei classification and in the case of Chondrichthyes, Nelson (2006). More recent and perhaps, ‘radical’ phylogenetic classifications (e.g. Betancur-R et al. 2013) are mentioned, and reasons for not adopting them are also presented. The following statement, with which I totally agree, is particularly appealing (p. XIX): ‘As a consequence of this burgeoning of new ideas about fish relationships, the time is ripe for a morphological renaissance in ichthyology’. In fact, students (and professionals alike) should ideally be aware of what has been perceived by a substantial portion of the ichthyological community as a negative side-effect of a seemingly ‘strict devotion’ to molecules and new technologies to the detriment of more integrative, biological approaches to understanding fish diversity (e.g. de Carvalho & Ebach 2009). The main purpose of the book, which is to provide a family-level visual identification guide to fish diversity based on the combination of external anatomical features, is also in accordance with the classifications adopted. However, in view of the arguments presented by the authors, I found it somewhat contradictory that the phylogeny depicted for the Chondrichthyes (p. 20) represents sharks (‘Selachii’) as monophyletic, because morphological cladistic studies clearly indicate that rays (Batoidea) form a distinct, monophyletic assemblage, nested within a paraphyletic shark-like group. The reference to Aschliman et al. (2012) in that figure is also apparently wrong; monophyly of the ‘shark clade’ is not implied by their data, even though other molecular studies have recovered that topology (see Li et al. (2012) for a summary of conflicting ideas about elasmobranch phylogeny). Similarly, reference to the phylogenomic phylogeny of the Actinopterygii of Faircloth et al. (2013) (p. 56) is concordant at that level with Grande's (2010) detailed monograph on the morphology and relationships of gars (Lepisosteiformes) and related forms, which eventually resulted in the resurrection of the Holostei in a modern phylogenetic perspective. Grande (2010) is cited only as one of the references in the Lepisosteidae section (p. 61), in spite of its unquestionable relevance to the understanding of the phylogenetic relationships among basal actinopterygians. The introduction is followed by an 11-page long, richly illustrated section devoted to the basic external anatomy of fishes, including types of body shapes, fin shapes and fin-ray terminology, mouth positions and standard measurements used throughout the book. In that section, a brief and useful description of the sensory and skeletal systems of fishes is also presented.

The core of the book is composed of more than 200 richly illustrated pages with basic information on the identification of approximately 130 families in 81 orders of fishes plus the ‘Chromides’, a coverage that presumably includes all larger groups of fishes according to the classifications adopted. Diagnostic features of the external anatomy are clearly presented and indicated in more than 200 plates depicting collection-preserved specimens and some X-ray images. The lack of pictures of live specimens might be a drawback to the non-specialist, but in addition to being extremely helpful when dealing with specimen identification in scientific collections, most diagnostic features indicated can be easily perceived in live or fresh specimens. Any ‘fish enthusiast’ would also definitely rejoice with the inclusion of some fantastic plates, such as those of the Bristlemouths, Hatchetfishes and Barbeled Dragonfishes (Stomiiformes: pp. 98–100), Seahorses, Sea Dragons and Shrimpfishes (Syngnathiformes: pp. 134–35), Deep-sea Anglerfishes (Ceratioidei: p. 221), and Triggerfishes (Balistidae: p. 229). Information on the diversity, representative genera, distribution, habitat and remarks on each group are also presented. The relevance of the guide as an introductory tool to fish taxonomy and identification is definitely indisputable.

However, the contents of the book would perhaps be more attractive to a broader, worldwide audience if the taxonomic coverage included more examples of groups found in the southern hemisphere. As an example, two of the three lamprey families (Mordaciidae and Geotriidae) are found exclusively in southern South America and Oceania. Even though they are mentioned in the introduction to the Petromyzontiformes (p. 16), only the Petromyzontidae (Northern Lampreys) is more adequately reviewed and illustrated. Similarly, only the Hiodontidae, a small, but phylogenetically relevant North American family of the Osteoglossomorpha, is treated in detail, but the Mormyridae, Notopteridae, Osteoglossidae and Gymnarchidae, which includes more than 240 mostly southern hemisphere species, are briefly mentioned under Osteoglossiformes (p. 63). In addition, only selected families or more inclusive groups of highly diverse clades, such as the Anguilliformes, Characiformes and Labriformes, are described in detail, even though concise coverage of the diversity of those groups is succinctly presented. However, as mentioned earlier, fish diversity is impressive; therefore, editors or authors of a guide like this inevitably have to decide which groups deserve more attention in detriment to others. The literature indicated in the introductory entries of all orders is also relevant and updated, and can be consulted if the reader feels more information is necessary. The book closes with a five-page glossary of technical terms and the list of references.

Summing up, Fishes: A Guide to Their Diversity is a technically accurate and nicely presented book, quite useful in introductory courses on fish diversity, but whose potential audience includes the non-specialist as well. One selected feature of the book that certainly deserves praise is the use of carefully prepared photographs of collection-preserved specimens. This is not only in accordance with the main goal of the book, but is also a testimony to the timeless relevance of collection-based science, a topic particularly pertinent in times where biological collections are sometimes unjustifiably deemed as secondary (see Rocha et al. 2014 for a recent review on that topic).