An Updated Classification of the Recent Crustacea By Joel W. Martin and George E. Davis Natural History Museum of Los Angeles County Science Series 39 December 14, 2001 AN UPDATED CLASSIFICATION OF THE RECENT CRUSTACEA Cover Illustration: Lepidurus packardi, a notostracan branchiopod from an ephemeral pool in the Central Valley of California. Original illustration by Joel W. Marin. AN UPDATED CLASSIFICATION OF THE RECENT CRUSTACEA BY JOEL W. M ARTIN AND GEORGE E. DAVIS NO. 39 SCIENCE SERIES NATURAL HISTORY MUSEUM OF LOS ANGELES COUNTY SCIENTIFIC PUBLICATIONS COMMITTEE NATURAL HISTORY MUSEUM OF LOS ANGELES COUNTY John Heyning, Deputy Director for Research and Collections John M. Harris, Committee Chairman Brian V. Brown Kenneth E. Campbell Kirk Fitzhugh Karen Wise K. Victoria Brown, Managing Editor Natural History Museum of Los Angeles County Los Angeles, California 90007 ISSN 1-891276-27-1 Published on 14 December 2001 Printed in the United States of America PREFACE For anyone with interests in a group of organisms such knowledge would shed no light on the actual as large and diverse as the Crustacea, it is difficult biology of these fascinating animals: their behavior, to grasp the enormity of the entire taxon at one feeding, locomotion, reproduction; their relation- time. Those who work on crustaceans usually spe- ships to other organisms; their adaptations to the cialize in only one small corner of the field. Even environment; and other facets of their existence though I am sometimes considered a specialist on that fall under the heading of biodiversity. crabs, the truth is I can profess some special knowl- By producing this volume we are attempting to edge about only a relatively few species in one or update an existing classification, produced by Tom two families, with forays into other groups of crabs Bowman and Larry Abele (1982), in order to ar- and other crustaceans. Crabs are but a small picture range and update the Crustacea collection of the of the overall diversity of the Crustacea. They rep- Natural History Museum of Los Angeles County. resent only one infraorder [Brachyura] within one This enormous and diverse collection contains an order [Decapoda] within one superorder [Eucarida] estimated four to five million specimens, making it within one subclass [Eumalacostraca] within one the second largest collection of Crustacea in the class [Malacostraca] of the six currently recognized Americas. While undertaking this task, it occurred classes of the Crustacea (as depicted herein). I am to us that others might benefit from our efforts, and certain that this situation is similar for all other that perhaps a general update on the number and crustacean systematists, with the result that there arrangement of the living crustacean families, along are no living specialists who can truly claim to have with an explanation of the systematic and classifi- an in-depth understanding of the Crustacea as a catory changes suggested during the last two de- whole. cades, might be a welcome addition to the litera- This volume is an attempt to provide the reader, ture. I hope this volume is seen as nothing more whether a seasoned systematist or a beginning stu- than the briefest of introductions into an under- dent, with a glimpse into the enormous variety of standing of crustaceans and that it might lead to extant crustaceans. The sheer number of categories further work not only on the relationships among that humans have constructed to contain and order crustaceans but also toward understanding the this group is some indication of the incredible overall picture of crustacean biodiversity and nat- amount of morphological diversity they exhibit. ural history. But this is only a small part of the overall picture. Joel W. Martin Even if one were to grasp the full range of taxo- June 2001 nomic diversity as presented in this classification, Los Angeles, California ACKNOWLEDGMENTS We sincerely thank the many carcinologists to pods; Gary Poore for information and literature on whom we sent earlier versions of the classification several peracarid and decapod groups and for his (all of whom are listed in Appendix II). Although detailed review of our penultimate draft; Robert not all of these persons responded to our queries Hessler for providing needed literature and for his (we had a response rate of approximately 60% to insightful suggestions; and Lipke Holthuis for sug- the first mailing and approximately 70% to the sec- gesting corrections to several taxonomic authorities ond) and some saw only later versions, we felt it and dates in our earlier versions. Obviously, not all appropriate to list all persons from whom com- of the suggestions we received were incorporated, ments were solicited. Drs. Rodney Feldmann and in part because some suggested changes contradict- Geoffrey Boxshall, in addition to commenting on ed others and in part because some suggested sections of the classification, served as external ref- changes would have involved major rearrange- erees for the entire manuscript, and to both we are ments for which we deemed the evidence insuffi- extremely grateful. We mourn the loss of Erik Dahl cient or incomplete. Inclusion of crustacean-related in January 1999, of Mihai Ba˘cescu in August 1999, web sites as an appendix was the idea of Keith of Arthur Humes and Austin Williams in October Crandall. We thank Todd Zimmerman, Regina 1999, of Gary Brusca and Ray Manning in January Wetzer, Todd Haney, and Sandra Trautwein in our 2000, of The´odore Monod in November 2000, and Los Angeles crustacean laboratory for suggestions of Denton Belk in April 2001, during the compi- and assistance at various points; Regina Wetzer in lation of this classification. Their absence is keenly particular was instrumental in assembling Appen- dix III. felt by all carcinologists. Deserving of special rec- We thank the Natural History Museum of Los ognition are David K. Camp for supplying much Angeles County, and especially John Heyning, John needed information and literature for a wide vari- Harris, and the members of the Scientific Publica- ety of taxa; Anne C. Cohen for literature on ostra- tions Committee, for support and for assistance codes and maxillopods and for enlightening discus- with readying the manuscript for publication. We sions of that group’s presumed monophyly; William also thank the National Science Foundation for Newman and Mark Grygier, both of whom provid- partial support via grants DEB 9020088, DEB ed literature and enlightening comments on maxil- 9320397, and DEB 9727188 to J. W. Martin; NSF lopods; Mark Grygier for additional comments on Biotic Surveys and Inventories grant DEB 9972100 interpretation of ICZN recommendations; Trisha to T. L. Zimmerman and J. W. Martin; and NSF Spears and Cheryl Morrison for providing unpub- PEET grant DEB 9978193 to J. W. Martin and D. lished molecular sequence or gene rearrangement K. Jacobs. Finally, we sincerely thank Sue, Alex, data for the decapods; Geoffrey Fryer for his al- and Paul Martin and Ruthe Davis for their kind ways direct comments concerning the branchio- encouragement and understanding. CONTENTS Preface ......................................................................................................................... v Acknowledgments ......................................................................................................... vii General Introduction....................................................................................................... 1 Methods ................................................................................................................... 3 Names, Dates, and the ICZN......................................................................................... 3 Cladistics and Classification of the Crustacea ..................................................................... 5 Molecular Systematics and Classification of the Crustacea ..................................................... 7 Developmental Genetics and Classification of the Crustacea ................................................... 8 Sperm Morphology and Classification of the Crustacea......................................................... 8 Larval Morphology and Classification of the Crustacea......................................................... 9 The Fossil Record and Classification of the Crustacea.......................................................... 10 A Note on the Appendices ........................................................................................... 10 Rationale .................................................................................................................... 12 Concluding Remarks...................................................................................................... 57 Classification of the Recent Crustacea ................................................................................ 58 Literature Cited ............................................................................................................ 76 Appendix I: Comments and Opinions............................................................................... 102 Appendix II: List of Contributors .................................................................................... 114 Appendix III: Other Crustacean Resources......................................................................... 115 An Updated Classification of the Recent Crustacea By JOEL W. M ARTIN1 AND GEORGE E. DAVIS1 ABSTRACT. An updated classification of the Crustacea down