ENCYCLOPEDIAOFSOUTHAMERICANAQUATICINSECTS: EPHEMEROPTERA Encyclopedia of South American Aquatic Insects: Ephemeroptera lllustrated Keys to Known Families, Genera, and Species in South America by w. Charles Heckman Forestry Sciences Laboratory ~ " SPRINGER-SCIENCE+BUSINESS MEDIA, B.V. A C.I.P. Catalogue record for this book is available from the Library of Congress. ISBN 978-94-010-3928-4 ISBN 978-94-010-0528-9 (eBook) DOI 10.1007/978-94-010-0528-9 Cover: One of the earliest color ilIustrations of a South American mayf1y: Siphlonella guttta, as illustrated by Pietet (1843-45) Printed on acid-free paper AH Rights Reserved © 2002 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 2002 Softcover reprint of the hardcover lst edition 2002 No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, mierofilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Thisbookisdedicated tomymother, RuthA.Heckman forhersupportthatpermittedthecompletionofthisvolume. Contents Introduction 1 Anappealforqualityintaxonomic work .4 Scopeofthework 8 Acknowledgements 10 Literature 10 Section2:Ephemeroptera '" 11 2.1 Morphology 13 2.2Ecology 22 2.3Preservationandexamination 22 2.4Taxonomic problems 24 2.5Suggestionsforimprovement. 25 2.6Keytothefamilies 27 Adults 27 Larvae 37 Euthyplociidae '" 45 Polymitarcyidae '" 51 Ephemeridae 87 Leptohyphidae 88 Oligoneuriidae .143 Siphlonuridae 156 Ameletopsidae 158 Vlll Baetidae 160 Leptophlebiidae 232 Caenidae .367 Oniscigastridae 387 Literature .389 Index .408 Introduction This work was begunto provide keystothe aquatic insect species known from Brazil. The original goal was to include all genera known from South America and all species from Brazil, but for most groups, the scope was expanded to encompass all species in South America, and, in some cases, to include terrestrial species oforders comprising both terrestrial and aquatic taxa. In no case is a taxonomic revision of any group undertaken, although recommendations for such revisions are included where appropriate, and probable synonymy ofnominal species still treated as valid in the literature is noted. Two different approaches will be employed according to the taxon being treated. For phylogenetic groups encompassing overwhelmingly or exclusively aquatic species, such as the orders Plecoptera and Ephemeroptera or the families Dytiscidae and Culicidae, keys are provided to distinguish all genera and species known to occur in South America. An effort has been made to include every identifiable species so that the user ofthe keycan determine with reasonable certainty whether or not his specimen belongs to a species that has already been described or whether it is one that is not yet known to science. Where feasible, complete keys will be prepared for groups containing both aquatic and terrestrial species that do not encompass an extraordinarily large number ofspecies. This hasalready beendone forthe order Collembola. The second approach will be used for aquatic species belonging to predominantly terrestrial taxa, such as the order Lepidoptera or the families Curculionidae and Muscidae. In such cases, the number ofterrestrial species involved is too great to deal with conveniently. For example, a work confined to aquatic insects cannot include akeyto alloftheapproximately45,000 weevil species (O'Brien and Wibmer, 1978)or even the portion ofits enormous fauna inhabiting South America because only a small percentage ofthem live inor on aquatic plants. However, without such a comprehensive key, it becomes difficultfor a person not specializing inthe taxonomy ofthis group to besure in which genus or subfamily his specimen belongs. For aquatic species in such groups, a descriptive approach is used. An attempt has been made to describe the morphology completely enough for the non-specialist to recognize his aquatic species. At the same time, descriptions or keys to higher taxa within these groups are provided as necessary so that the aquatic species can be distinguished from the terrestrial ones and phylogenetic affinities of the specimens can berecognized. The geographical limitations of this work are not strictly maintained throughout. For some genera, keys are provided that include mention or descriptions of species still known only from Central America or Caribbean islands, while for others, the keys are strictly limited to the South American fauna. The choice ofcomprehensiveness was dictated mainly by convenience. For genera encompassing few species and those that have been revised by competent taxonomists, keys to most or all Neotropical species could easily be 1 2 provided. In the cases ofother genera encompassing poorly described species, those which have not been reported south ofPanama and the Antilles were not included inthe keys. In general, the ranges of the aquatic insect species are very poorly known. The reported occurrences indicate more the locations at which entomologists have worked than the actual distribution ofthe species. The type specimens of a great many South American species were collected during expeditions to individual regions of the continent, and systematic surveys ofthe fauna have only been undertaken for a few groups. Among the prominent early collectors was Charles Darwin. Larger expeditions were undertaken during the late 19th zo" and early century. Considerable numbers of species have been described after examination of the specimens collected in Patagonia and South Chile during the early part ofthe 20th century. In Brazil, Rio de Janeiro and Santa Catarina appear very frequently inthe distribution reports due to the extensive collection in those states by F. Plaumann, while many other species were described from Amazonas because ofthe presence ofa large research station, the Instituto Nacional de Pesquisas da Amazonia, at Manaus. Naturally, a great many species were described from specimens collected at Sao Paulo and Rio de Janeiro, where most ofthe Brazilian institutes ofresearch are located. Reports from other Brazilian states are generally much rarer, so the ranges ofBrazilian species can generally be expected to be much more extensive than indicated by the published reports. Notable research efforts in other parts ofSouth America have resulted in large numbers ofspecies being recorded for Surinam and the Amazon region of Peru. Knowledge of the fauna in other regions varies considerably from taxon to taxon, depending upon the efforts of talented individuals specializing in individual orders or families. Generally, the insect taxa with the greatest impacton public health and agriculture are best known. For some rarer species inneglected taxa,the ranges are scarcely defined atall. Specimens described during the last century were sometimes reported from "Brazil" or even "South America" without any more exact collecting data. The fact that the descriptions ofsuch species are generally sketchy, at best, makes it doubtful whether they can be recognized again. There is mention in many of the review papers cited in this work about the confusion caused by falsely labelled specimens, incomplete collecting data, and doubt among the collectors about the names ofthe places from which their specimens originated. Names such as "Chapada" in Brazil frequently appear without mention of which Chapada is meant. This problem will continue to cause confusion inthe future as ithas inthe past. The problems encountered in systematic biology worldwide are especially pronounced in the Neotropical Region. This is due to the dearth ofcompetent taxonomic studies on the regional fauna. Theoretically, the scientistwho needs to know the correct name ofaspecimen can accomplish this by a procedure that assures a high probability ofsuccess, although a good deal oftime and expense may be required. The first step inthis procedure isthe use ofa comprehensive key treating the higher taxon to which the specimen belongs. This process is 3 much easier for aspecialist familiar with the groupthan for a person who needs to know the identity of species being used in physiological experiments or surveyed insynecological studies. Inmost cases, after the specimens have been identified using the keys, original or revised descriptions listed by the author of the key should be consulted to confirm the identifications. If the available descriptions are so poor that the identity of the species remains uncertain, a comprehensive taxonomic review ofthe taxon it belongs to must be consulted. Ifsuch a review has not yet been published, the specimen to be identified must be compared with type specimens ofeach species belonging to the higher taxon to which the specimen belongs. These should befound inmuseum collections. According to taxonomic convention, the author of a published original description of a new species should designate one of his specimens as a holotype. This type then becomes the standard on which the identifications of all specimens collected in the future are based. The species to which the holotype belongs isthen referred to bythe name proposed bythe author, at least whenthe same namehas not previously been applied to another species. Inaddition to the holotype, other specimens believed to beofthe samespecies by the author are designated as paratypes. If a holotype is not available, a paratype can be examined to confirm identifications. If the holotype has been lost or extensively damaged, a specialist revising the taxonomy of the group maydesignate a lectotype apparently belonging to the species inquestion. This then replaces the holotype as a standard for recognizing the species, at least untilthe lost holotype orparatype isfound. Anyone wishing to take the trouble to identify a specimen beyond the shadow ofareasonable doubt should beabletofollow this procedure. Ifhis specimen is not the same species as any ofthe holotypes preserved in museums, he should prepare a description ofhis specimen and have it published with his proposed nameforthe newspecies or give itto aspecialistwho isinterested indoing this. Unfortunately, the procedures described above often fail to work, especially when South American insects are involved. First of all, keys to identify the species are seldom available, and when they are, they are generally out ofdate or incomplete for the region being studied. This leaves the researcher with the chore of collecting a large number of original descriptions to match with his specimens. These descriptions are sometimes very sketchy, leaving the reader with no reliable way of identifying his specimen from the available literature. Comparisons with type specimens may not only be difficult in many cases because the typeswere deposited inmuseumsonother continents,they are often impossible because some authors have failed to mention the name of the museum in which they intended to place their type specimens or because the specimen cannot be found again due to war damage or sloppiness by the curators ofthe museum inquestion. Even when the type can be found, itoften proves to be in very poor condition, and relatively few paratypes of South American species have been designated that can be examined inthe absence of ausable holotype. 4 Using established procedures for identifying South American insects is made even more problematic by the practice of some authors of describing new species on the basis ofonly one life stage. Not only have many species been described by taxonomists who examined only adults, some are known only from larvae. Furthermore, countless species are known only from adults ofone sex. While the description ofan adult may provide a legitimate basis for establishing a new species, it isdifficult to findjustification for naming a species based only on larvae. Some authors have designated larvae as the types of species congeneric with others known only as adults. These individuals seemed to be in such a hurry to publish that they deliberately left the arduous task ofmatching larvae with adults to other researchers. In practice, convention should dictate which gender and life stage should be chosen as the holotype. For example, adult male chironomids are presently those on which species descriptions should be based. Earlier descriptions of female adults are generally useless for determining a species unless someone has taken the trouble to match the female to a described male. In an ideal system ofnomenclature, descriptions ofadults of both sexes and ofthe larval stages should be provided. However,the state ofthe art still requires specimens to be identified according to partial descriptions ofone stage and often one sex. Therefore, before fully workable systems for identifying South American species will be possible, an enormous number of revisions and supplemental descriptions will be necessary. This work ismeant as a first step in the process: providingkeys asreliable asthe available publications permit. Finally, it is necessary to note that no keys to taxa higher than family are provided in this work. Keys to the insect orders are difficult to prepare and use because of the many exceptions to the general morphological characteristics, such as wingless dipterans and heteropterans as well as ephemeropterans that lack legs. Descriptions ofthe orders can be found in any number oftextbooks on entomology or invertebrate zoology, and most specimens can be quickly assigned to the correct higher taxon by browsing the volumes ofthis series and comparing them to the illustrations. With a little experience, anyone can learn to recognize the order ofan insect almost at aglance. An appeal for quality in taxonomic work This appeal is addressed to two groups, the first consisting of those responsible for deciding who obtains what portion of the available research funds and the second being the taxonomists themselves. It has long been recognized byexperiencedecologiststhat identification ofthe species present in a community isan absolute necessity for thorough ecological research. The biota ofany water body, for example, is more than a quantity of "biomass" or a "pathway for energy". Many ecologists, especially those beginning their research careers, have the greatest difficulty in identifying the species present, and the quality oftheir work is limited by this difficulty. The