Polychaete Worms Definitions and Keys to the Orders, Families and Genera

THE POLYCHAETE WORMS DEFINITIONS AND KEYS TO THE ORDERS, FAMILIES AND GENERA THE POLYCHAETE WORMS Definitions and Keys to the Orders, Families and Genera By Kristian Fauchald NATURAL HISTORY MUSEUM OF LOS ANGELES COUNTY In Conjunction With THE ALLAN HANCOCK FOUNDATION UNIVERSITY OF SOUTHERN CALIFORNIA Science Series 28 February 3, 1977 TABLE OF CONTENTS PREFACE vii ACKNOWLEDGMENTS ix INTRODUCTION 1 CHARACTERS USED TO DEFINE HIGHER TAXA 2 CLASSIFICATION OF POLYCHAETES 7 ORDERS OF POLYCHAETES 9 KEY TO FAMILIES 9 ORDER ORBINIIDA 14 ORDER CTENODRILIDA 19 ORDER PSAMMODRILIDA 20 ORDER COSSURIDA 21 ORDER SPIONIDA 21 ORDER CAPITELLIDA 31 ORDER OPHELIIDA 41 ORDER PHYLLODOCIDA 45 ORDER AMPHINOMIDA 100 ORDER SPINTHERIDA 103 ORDER EUNICIDA 104 ORDER STERNASPIDA 114 ORDER OWENIIDA 114 ORDER FLABELLIGERIDA 115 ORDER FAUVELIOPSIDA 117 ORDER TEREBELLIDA 118 ORDER SABELLIDA 135 FIVE "ARCHIANNELIDAN" FAMILIES 152 GLOSSARY 156 LITERATURE CITED 161 INDEX 180 Preface THE STUDY of polychaetes used to be a leisurely I apologize to my fellow polychaete workers for occupation, practised calmly and slowly, and introducing a complex superstructure in a group which the presence of these worms hardly ever pene- so far has been remarkably innocent of such frills. A trated the consciousness of any but the small group great number of very sound partial schemes have been of invertebrate zoologists and phylogenetlcists inter- suggested from time to time. These have been only ested in annulated creatures. This is hardly the case partially considered. The discussion is complex enough any longer. without the inclusion of speculations as to how each Studies of marine benthos have demonstrated that author would have completed his or her scheme, pro- these animals may be wholly dominant both in num- vided that he or she had had the evidence and inclina- bers of species and in numbers of specimens. In some tion to do so. areas they are even dominant in biomass. If any .state- ments are to be made about the biology of the benthic Kristian Fauchald environments, some note must be taken of the polychaetes. Furthermore, the keeping of some of these 19 May 1976 animals in culture has proved feasible, and some Los Angeles polychaetes even have become famous for their value as test animals in polluted areas. The development of some polychaetes appears to be genetically interest- ing, and studies of evolutionary rates and genotypic and phenotypic adaptations in these worms may prove very illuminating to our understanding of the benthic environment. All of these developments make it important that the major morphological and anatomical features be well understood, and preferably that the terminology and taxonomic categories be agreed upon by most workers. This review is an attempt at summarizing current information about the taxonomy and morphol- ogy of these animals. During the reviewing process, it became painfully obvious to me how exceedingly poorly known the group is and how few generaliza- tions can be made on the ecology and evolution of the polychaetes. I hope this review will bring forth a spate of investigations, by persons wishing to prove me wrong in my phylogenetic speculations, but also by persons willing to put in the hard work needed to fill in the gaps in our knowledge. Acknowledgments THIS REvíEW is a direct outcome of a lecture I gave during a class in polychaete biology at Santa Catalina Marine Biological Laboratory in 1973. It has benefited greatly from discussions with all of the students in the class, but perhaps especially Bill Kennedy was instrumental in pushing me into giving the lecture in the first place. 1 have also discussed parts of the paper with Ray Emerson, Tom Kauwiing, Fred Piltz and Bob Smith. My co-teacher at Catalina, Paul C. Schroe- der, was a great help in formulating some of these ideas. Some of the ideas presented here were also discussed with the late Dr. Olga Hartman, whose sound advice was always valued by me. Dr. Pat Hutchings advised me of some errors in the terebellid key, for which I am grateful. The good illustrations were made by Ms. Catherine Link; the others I am responsible for. Ms. Jo Anne Woodcock expertly typed most of the manuscript, prepared the index and cleaned up my English where needed, for which I am grateful. I am also very grateful to Mr. R. Edward Ostermeyer for seeing the paper through. I would wish to thank Dr. Robert J. Lavenberg, Natural History Museum of Los Angeles County, for prodding me into writing this book in this format and for his constant encouragement and enthusiasm for what grew from a moderately long key to families to a rather more massive offering. I am also very grateful to Dr. Bernard C. Abbott, Allan Hancock Foundation, Uni- versity of Southern California, for his support and enthusiasm and for letting me have the time to do the writing on this paper. THE POLYCHAETE WORMS DEFINITIONS AND KEYS TO THE ORDERS, FAMILIES AND GENERA^ By KRISTIAN FAUCHALD^ ABSTRACT; A review of the classification of the Class Polychaeta (Annelida) with comments on the characters used to identify the different included taxa has led lo the recognition of seventeen orders. All taxa down to the generic level are defined and a phylogenetic sequence suggested. Keys are presented to the families and genera of the Polychaetes. INTRODUCTION and the setae, if present, only rarely occur in bundles. These two groups were considered more advanced Polychaeta is part of the old, diffuse concept Verines, than the marine, dioecious polychaetes. The poly- a group that perhaps can best be defined as comprising chaetes have been defined for the last seventy years all animals that are longer than wide and non-vertebrate. as dioecious, marine annelids with parapodia bearing For the last seventy years or so, the polychaetes have numerous setae. They also should have anterior appen- been grouped with the oligochaetes and hirudineans and dages of various sorts (antennae, palps, tentacular a few smaller groups into the phylum Annelida. This cirri) and the gonadal ducts should be simple. phylum contains .segmented, coelomate worms in which These definitions work if some of the smaller groups a secondary loss of segmentation may have taken place, are disregarded. If these groups are taken into account, but in which traces of such segmentation at least can be as they must, the only separation that consistently can recognized internally. Other, more formal definition be made between the oligochaetes/leeches and the of the phylum can be found in standard text-books. polychaetes, is the presence in the former grouping Definition of the annelid classes has varied, however, of hermaphroditic gonads limited to a few segments. everyday recognition of members of the three major Some hermaphroditic polychaetes are known, but these classes has never been a problem: The Hirudinea con- usually have gonads in a large fraction of the total num- tains the leeches, the Oligochaeta the earthworms and ber of segments. It is then difficult to give a good, their allies, and the Polychaeta marine worms, such consistent and practically useful definition of what as the sand worm (nereids) and bloodworms (glycerids) is meant by a polychaete, but a definition along the used for bait in parts of the world. The three classes lines suggested below, should separate them from the appeared also, at least grossly, to be separated ecolog- other annelids with reasonable accuracy. ically in that the leeches were supposed to be parasitic, The polychaetes are multi-segmented annelids with the earthworms terrestrial and the polychaetes were parapodia; setae are present in distinct fascicles. They most common in the marine environment. This separa- are dioecious and have simple exit ducts from the tion is obviously unsatisfactory and as information about these animals accumulated towards the end of the last century, most workers settled on a grouping which associated the leeches and the earthworms with 'REVIEW COMMITTEE FOR THIS SCIENCE SERIES each other in one group opposed to the polychaetes. ROBERT J. LAVENBERG Members of both the former classes are hermaphroditic DONALD REISCH and have various complex glands associated with repro- ^Allan Hancock Foundation, University of Southern California. duction. Furthermore, both leeches and earthworms Los Angeles, California, 90007. Contribution Number 358 of lack parapodia (fleshy unjointed segmental appendages) the Allan Hancock Foundation. NATURAL HISTORY MUSEUM OF LOS ANGELES COUNTY Science Series 28 gonads. They are usually marine, more rarely fresh- 1962, pp. 424-425; Clark 1969, p. 47). Polychaete water and only rarely terrestrial or parasitic in habitat. taxonomists have tended to disregard these attempts Any of these features need not be present and none of and have continued to treat the polychaetes as if the them is essential for the recognition of an animal as class consisted of two orders (Fauvel 1958, pp. 166- a polychaete. 190; Hartmann-Schröder 1971, p. 29) or subclasses This topic has been treated in considerably greater (Uschakov 1955a), or have treated the group as if it detail by Clark (1969) and to a lesser extent by Fau- consisted of about 75 distinct and unrelated families chald (1974a). (Hartman 1968, 1969). The problem with all proposed A key morphological feature and at the same time schemes is that they are internally inconsistent. Fur- one of the most important taxonomic characters of the thermore, they give no better solutions to classificatory polychaetes is the setal (chaetal) construction. The problems than the old, admittedly anificial, separation setae are ectodermal derivatives, formed by ectodermal into two orders. cells that during the development have migrated to a The three most ambitious recent proposais were by position well below the rest of the ectodermally derived Dales (1962), Storch (1968) and Clark (1969). Dales epidermis. Each seta consists of a bundle of filaments used the variable structures of the eversible stomodeal laid down by a basal chaetoblast and up to several region (pharynx) to separate different groups.

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