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STRAMINIPILOUS FUNGI Straminipilous Fungi

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STRAMINIPILOUS FUNGI Straminipilous Fungi STRAMINIPILOUS FUNGI Straminipilous Fungi Systematics of the Peronosporomycetes Including Accounts of the Marine Straminipilous Protists, the Plasmodiophorids and Similar Organisms by Michael W. Dick University of Reading ,• SPRINGER-SCIENCE+BUSINESS MEDIA, BY Library of Congress Cataloging-in-Publication Data Dick,M. W. Straminipilous fungi : systematics ofthe peronosporomycetes, including accounts of the marine straminipilous protests, the plasmodiophorids, and similar organisms / by Michael W. Dick. p.cm. Includes bibliographical references (p. ). ISBN 978-90-481-5639-9 ISBN 978-94-015-9733-3 (eBook) DOI 10.1007/978-94-015-9733-3 1. Straminipilous fungi. 1. Title. QK604.2.S86 D53 2001 579.5'3--dc21 00-066290 ISBN 978-90-481-5639-9 Cover design: Prof. Michael W. Dick Printed an acid-free paper Ali Rights Reserved © 2001 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 2001 Softcover reprint of the hardcover I st edition 2001 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording Of by any information storage and retrieval system, without written permis sion from the copyright owner. PREFACE Monographs of flagellate fungi have had their origins in the monographs of Schroter (1892-1893), Fischer (1892a, b) and von Minden (1911-1915). The second edition of Aquatic Phycomycetes (Sparrow, 1960) was in its final proof-stages when I was a post-doctoral instructor in Dr Sparrow's laboratory. Karling's monographs, on the lagenidiaceous fungi (1942a, 1981), the Synchytriaceae (1964d), the Plasmodiophorales (1942b, 1968e) and the chytrids (1977) are now also dated. Much has changed: new species have been described; new concepts of species and kingdom interrelationships are rapidly developing, and codes of nomenclature for plants and animals have also changed during the intervening years of the 20th century. The invaluable works of Karling and Sparrow had limitations: the later work of Karling was sadly marred by incorrect citations and inaccurate copies of original art-work. Sparrow gave limited coverage to the filamentous biflagellate taxa and endobiotic monads, so that his identification keys, based on family and genus concepts, could sometimes be misleading. Many monographs have given abbreviated citations of the first descriptions of species without backup of the full reference (title and full pagination) in the bibliography. This practice may have saved paper but it greatly increases the length of time it takes to trace and obtain the original publications. To help future taxonomists, and particularly users of taxonomy, I have given entries with the authority unabbreviated and the journal title in full. In view of the often confused history of generic concepts, I have also given an extended synonymy under generic entries. In the past, the names of authorities for taxa have been more or less arbitrarily abbreviated. There are now comprehensive 'recommended' lists that can be followed, but they are still not universally recognized. For these reasons all citations are also listed alphabetically in the BIBLIOGRAPHY. APPENDIX 1 provides a 'binomials list' using the recommended authority abbreviation and APPENDIX 2 gives the recommended form for the authorities for all known straminipilous fungi. Journal abbreviations are not given because so many of the entries predate the BIOSIS files; librarians find it easier to trace full titles, and different journals follow different journal-abbreviation guide lines. I believe that identification keys, rather than lengthy descriptions of species, provide the best initial introduction to the taxa. In most cases workers will then need to consult several publications in addition to the first publication. Comprehensive bibliographies for each species are included under each binomial. Illustrations are sometimes of such indifferent quality that I have preferred not to list them separately from these species references. Considerable artistic skill would be needed to provide recognizable portraits for the reduced morphology of the endobiotic parasites and this has not been attempted here; so many are known only from the original decriptions. The keys in this work are conceived from an ecological standpoint. I have therefore strayed outside the strict interpretation of straminipilous fungi, both in PART V: SYSTEMATICS and PART VI: KEYS (though to different extents) to indicate the relationships of organisms that at one time or another have been grouped, or perhaps confused, with the flagellate fungi. For practical identification of all of these small endobiotic flagellate fungi from natural habitats it is essential that the keys and systematic entries include the Olpidiales and part of the Blastocladiales of the Chytridiomycetes. Preparation of the chapter entitled Oomycota (Dick, 1990a) for the Handbook of Protoctista (Margulis et al., 1990) made me realize the extent of the disarray in the taxonomy of the biflagellate endobiotic parasites, most of which have, at one time or another, been placed in the order Lagenidiales. At first it seemed that a simple reorganization of taxa would be sufficient, but it became increasingly obvious that a much more substantial theoretical reappraisal would be needed. I have had to question the basic tenets of the classification of flagellate fungi which have been accepted throughout the last half century. Foremost of these has been the reliance on the primacy of zoospore flagellar number. The importance of flagellar ornamentation was not initially recognized. The possession of tubular tripartite hairs is now considered to v be of primary phylogenetic significance, and organisms possessing this feature are referred to as straminipiles (Patterson, 1989). Straminipilous ornamentation occurs on the anteriorly-directed flagellum of these fungi. Assignation to a major taxon has often depended on observations by earlier workers without serious consideration of the existence of correlating secondary characters. Parallel evolution was invoked to account for patterns of parasitism and distribution, with the result that 'examples' of 'parallel evolution' are scattered throughout the classification. Seldom are the examples of parallel evolution accompanied by those minor modifications of ontogeny or form that would justify the hypothesis. The frequency of the use of such an explanation is not credible: the alternative is to question the premise. More recently, the biochemical studies of the evolution of molecules at one extreme, and the recognition of coevolution of communities at the other extreme, have had their polemicists. All these approaches have their places, and each contributes to an understanding of the evolution of any group. It is not enough to cast doubt on primary precepts without substituting another hypothesis. I have suggested that anisokont flagellation (flagella of different lengths), leading to heterokont flagellation (flagella of different surface morphology involving straminipilous ornamentation), may be more fundamental to that group of the Protoctista from which the Kingdom Straminipila may have evolved. This, in turn, provokes a reconsideration of the diagnostic criteria for, and thus the delimitation of, the Straminipila, a problem which is not yet fully resolved. Incomplete loss of the flagellar apparatus, accepted as a probability by phycologists, may also have occurred in flagellate fungi. Thus, flagellar number could be of lesser significance than flagellar ornamentation or kinetosome organization: the inclusion of the Hyphochytriomycetes is therefore desirable. This work has three main aims. Thefirst aim is to review the diversity of morphology, morphogenesis and ultrastructure within the better-known biflagellate fungal taxa. PART I: CRITERIA FOR DIAGNOSES OF FLAGELLATE FUNGI thus also provides a source book for the general biology of the straminipilous fungi. The information at present available for the lagenidiaceous fungi is related to this framework. I hope that the discussion in PART II: CLASSIFICATIONS will help to bridge the divide between the zoological, phycological and mycological appproaches to evolutionary protistology by providing comprehensive coverage of the mycological references for non-mycologists. The systematic treatments (PART III: THE BETTER-KNOWN PERONOSPOROMYCETES and PART IV: THE LAGENIDIACEOUS FUNGI) differ in style because of the very different stages that their systematics have reached. Whereas the hitherto stable generic classifications, based on morphology, of the Peronosporales and Saprolegniales are now being overturned by molecular studies to the extent that it will not be possible to present an overview for another two or three years, perhaps in a supplementary volume; there is little chance that sufficient numbers of the lagenidiaceous fungi will be studied with these techniques: it is still necessary to try to provide a morphological framework for a transitional, traditional classification for the latter group. For both groups of these straminipilous fungi a nomenclatural framework is essential; this is provided here. The second objective is to present an hierarchical classification for as many as possible of the fungi left incertae sedis by the placement of the Lagenidiaceae in the Pythiales by Dick, Wong & Clark (1984). Brief reviews of the Olpidiopsidaceae, Sirolpidiaceae and other families are therefore relevant. The current generic integrity
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