Cycad Classification. Concepts and Recommendations

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Book Review

T Walters and R Osborne (eds)

2004, CABI Publishing, CAB International, Wallingford, Oxfordshire OX10 8DE, United Kingdom or 875 Massachusetts Avenue, 7th Floor, Cambridge, MA 02130, United States of America xvii + 267 pages, monochrome photographs, line drawings and diagrams ISBN 0-85199-741-4, price £55, US$100 (Hardcover) e-mail: [email protected], [email protected] Internet: http://www.cabi.org

This book is really the proceedings of a symposium hosted • C-J Chen, KD Hill and DW Stevenson: Comments on in March 2002 by the Montgomery Botanical Center in Miami Cycas, Dyerocycas and Epicycas (Cycadaceae). The in line with their endeavour to compile an ex situ collection recent separation of the genera Dyerocycas and Epicycas of cycads through representative sampling of populations. from Cycas by DJ de Laubenfels is demonstrated to be The aim of the symposium was to review our knowledge of based on slight characteristics which are not consistent cycad taxonomy, to identify information which is still unavail- with other features, and accordingly this is rejected. able, to decide on how future research should be shaped • P Vorster: Classification concepts in Encephalartos and to standardise procedures and presentation of reports (Zamiaceae). The available types of information which can so that the results of different taxonomists can be compared. be used for phylogenetic reconstruction are reviewed in Some 13 eminent cycad specialists from all over the world respect of current knowledge; and 18 geographical group- attended and read papers. ings which are likely to reflect taxonomic groupings, are Due to the different approaches followed by the respective listed. attendees, there is no continuous thread through the vol- • PI Forster: Classification concepts in Macrozamia ume, but the editors strived to unite the contributions by (Zamiaceae) from eastern Australia. Species concepts in means of the introductory chapter, ‘We hold these truths...’, this group are explained, and character states used for which explains the rationale behind the symposium and the identification purposes are listed. volume; and the last chapter, In search of the true tree: • LM Whitelock: Classification concepts in Ceratozamia guidelines for classification. (Zamiaceae). The taxonomic history of Ceratozamia is The subsequent 13 chapters are: reviewed. The characteristics hitherto used to distinguish • J Donaldson: Saving ghosts? Implications of taxonomic species are listed and illustrated, and criteria for descrip- uncertainty and shifting infrageneric concepts in the tions of new species are provided. Cycadales for Red Listing and conservation planning. The • AP Vovides, MA Pérez-Farrera, D Gonzáles and S thesis here is that for conservation to be successful, the Avendaño: Relationships and phytogeography in organisms to be conserved must be properly and perma- Ceratozamia (Zamiaceae). A postulated geographical nently defined. Unfortunately the circumscription of centre of origin as well as a cladogram of relationships are species change as our taxonomic knowledge about them based on geographical distribution, ecological data, mor- advances. phology, leaflet histology and DNA sequencing. • KD Hill: Character evolution, species recognition and • MA Pérez-Farrera, AP Vovides, L Hernández- classification concepts in the Cycadaceae. Analysis of Sandoval, D Gonzáles and M Martinez: A morphometric combined morphological and molecular datasets in the analysis of the Ceratozamia norstogii complex genus Cycas has yielded a cladogram with good resolu- (Zamiaceae). Three recently described but poorly circum- tion. Plotting characteristics used by previous authors in scribed species from adjacent geographical areas were developing infrageneric systems of classification allows an sampled through 90 individuals and were statistically independent assessment of the value of such characteris- analysed in respect of 20 morphological variables. The tics in taxonomy. Still, no classification system presented results reveal clear discontinuities, supporting recognition up to now agrees entirely with phylogenetic results. of all three species. • A Lindström: Morphological characters useful in deter- • TJ Gregory and J Chemnick: Hypotheses on the rela- mining species boundaries in Cycas (Cycadaceae). A tionship between biogeography and speciation in Dioon standardised set of taxonomically useful morphological (Zamiaceae). It is postulated that populations of Dioon characteristics is provided for circumscription of species. migrated upwards and downwards in elevation, as well as South African Journal of Botany 2004, 70: 676–677 677

laterally, in response to warming and cooling climatic There are two appendices: The world list of cycads, under cycles during the late Pleistocene and Holocene. This the authorships of Hill, Stevenson and Osborne, which is an sometimes led to disjunction and rapid speciation. annotated checklist of all recognised species, and a • P Caputo, S Cozzolino, P de Luca, A Moretti and DW Glossary of terms by Osborne and Walters. The volume Stevenson: Molecular phylogeny of Zamia (Zamiaceae). ends with an index. DNA analysis of 23 (out of approximately 58) species Interestingly the attendees were in agreement that at least resulted in poorly resolved clades, which nevertheless for the foreseeable future no subspecific ranking would be reveals a conflict between morphological and molecular recognised in the Cycadales. This really stems from the phi- data. The molecular data is broadly congruent with geo- losophy of RA Dyer (1987) during his research on graphical distribution. Encephalartos, where he reasoned that the recognition of • B Schutzman: Systematics of meso-American Zamia subspecific taxa in the cycads implies a closer relationship (Zamiaceae). Characteristics used by this author in the between the subspecific taxa of a species than between course of his taxonomic exploration of central American species, something which his knowledge could not confirm Zamia are assessed and pitfalls are pointed out. with certainty. Today this is still true, though molecular Unresolved species complexes are described and direc- results may eventually change it. Only after the symposium tives for future research suggested. did I realise that the recognition of the species as the lowest • DW Stevenson: Zamiaceae of Bolivia, Ecuador and Peru. rank is in line with cladistic doctrine. This is ironic, as during This is a straight taxonomic account of the known species this symposium Dr Kathy Kron of Wake Forest University of Zamia in Bolivia, Ecuador, and Peru. Eleven species gave a presentation on the proposed Phylocode [of nomen- are treated, including one new species. clature] which was unanimously and vigorously rejected by Each chapter has its own bibliography. all the attending taxonomists. Chapter 15, In search of the true tree: guidelines for clas- The book is printed on good quality matt paper and the sification, was edited by R Osborne and T Walters, but is photographs are beautifully clear. It is sturdily bound, though really a summary of discussions between all the participants. the glossy surface does not reflect the dignity of the con- It provides guidelines for taxonomic descriptions (very tents. important, since numbers of new species are described so For me as taxonomist this volume is useful because the poorly that they cannot be recognised from the descrip- concepts used by collaborators for cycad genera other than tions), for presenting reports (publishing), for collecting field Encephalartos on which I work, are clearly outlined. The aim data and for collecting and processing herbarium speci- of the symposium, to define and standardise taxonomic mens. While this is necessary in order to make research approaches for the Cycadales, means that treatments of dif- results usable and comparable, much of the guidelines have ferent genera in different parts of the world should hence- been applied for a long time already by professional taxono- forth be comparable. It also comes close to being a one-stop mists. The chapter ends with nine lists of, respectively, source of information on procedures for anyone doing Active cycad workers (with very wide limits), Major herbaria research on cycad taxonomy. It contains a great deal of use- with cycad accessions, Major ex situ [living] cycad collec- ful information on the different genera, though I guess that, tions, Major cycad fossil collections, Insect collections with at the current rate of research, much of the data will soon be significant cycad-associated specimens, Molecular laborato- out of date. The book will be less useful for taxonomists in ries carrying out cycad-related work, Software packages for general, or those working on other plant groups; but I pre- cladistic analysis, Cycad societies and magazines and Other sume that the volume is aimed primarily at that handful who cycad associated websites. are researching cycad taxonomy.

Piet Vorster Botany Department, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa e-mail: [email protected]