Orthocladiinae sensu lato (Diptera: Chironomidae) Keys to Central European larvae with respect to macroscopic characters Claus Orendt Thomas Bendt German Limnological Society (DGL) German Limnological Society (DGL) Orthocladiinae sensu lato (Diptera: Chironomidae) Orthocladiinae Prodiamesinae Diamesinae Buchonomyiinae Telmatogetoninae Podonominae Keys to Central European larvae with respect to macroscopic characters by Claus Orendt and Thomas Bendt DGL -Arbeitshilfe 1 -2020 DGL - Tools No. 1 -2020 Contents Page 3 Preface and Acknowledgements 5 Introduction 11 References 13 Glossary 17 Keys 95 Special keys 95 Cricotopu s and Orthocladius 108 Eukiefferiella 110 Halocladius 113 Metriocnemus 121 Nanocladius 122 Parakiefferiella 123 Psectrocladius 128 Rheocricotopus 131 Index All rights reserved. © 2020 Deutsche Gesellschaft für Limnologie e. V., Essen, Germany Printed by Printed in Germany ISBN 978-…. To be cited as: Orendt C., Bendt, Th. (2020): Orthocladiinae sensu lato (Orthocladiinae, Prodiamesinae, Diamesinae, Podonominae, Bu- chonomyiinae, Telmatogetoninae) (Diptera: Chironomidae). Keys to Central European larvae with respect to macroscopic characters . - DGL-Arbeitshilfen ( DGL Tools ) 1-2020, 140 p. German Limnological Society (DGL) e. V., Essen. ISBN 978-…. Authors' addresses: Dr. Claus Orendt, WaterBioAssessment, Brandvorwerkstr. 66, 04275 Leipzig, Germany; [email protected] Thomas Bendt, Heyerhütte 34, 47877 Willich, Germany; [email protected] Orders: Deutsche Gesellschaft für Limnologie e. V., Geschäftsstelle, Rellinghauser Str. 334f, 45136 Essen, Germany; phone +49-(0)201-61 76 30 51, fax +49-(0)201-61 76 30 53; email: [email protected] Preface and Acknowledgements 3 Until quite recently, the identification of ronomids as bio-indicators in freshwater Chironomidae larvae was a challenging monitoring has been known for a long and time-consuming business reserved for time (summarized earlier in Thienemann, specialists in certain academic positions. 1954), and their ecological preferences Although some monographic works (e.g. were classified for subsequent use in mon- Wiederholm et al., 1983, Pankratova, itoring programmes in several countries. 1970, 1977, 1983, Bíró, 1988, and others) Recently, efforts to base taxonomic identi- were available and of great value for the fication work on molecular methods prom- specialist, their use was frequently re- ised apparently easier and cheaper taxo- stricted to regions or required quite a lot nomic identification than using morpho- of time and effort to work successfully. logical characters. However, methodologi- Moreover, important information on taxo- cal restrictions revealed that this may be a nomic identification was scattered in many helpful tool only for special taxonomical single papers, which is, however, also true questions (e. g., the scientific discussion of at present. For beginners and those, who the taxonomical status of a morphological are not constantly working with larval type). In biomonitoring and practical work, identification, chironomids are a challeng- it is not applicable, as quantification of the ing taxonomic group but becoming easier community is not possible or not econom- with better keys and catalogues available. ical. Moreover, after some training, the Frequently, many problems in the recogni- single specimen collected can be quickly tion of characters resulted from drawings identified by observing morphological or illustrations which mostly show an ideal characters, to achieve a satisfactory taxo- picture differing in perspective and view nomic level identification. from the observed view, even when the This situation motivated us to help lower material is in good condition and well posi- the threshold for identification work of tioned. Taking photographs for illustra- chironomid larvae by providing a tool illus- tions required expensive equipment and trated mainly by colour photographs. In black-white format, which did not always 2012, a simliarly designed identification improved the images which depended also tool for Chironomini (Orendt & Spies, on the printing quality of the published 2012) was produced, in which we used book or Journal. Traditions of observation macroscopic characters leading to identifi- practice (e. g. mounting on a slide after a cation to genus, species groups, and easily maceration procedure) frequently require separable species, as far as possible. In our a time-consuming treatment prior to de- concept, we mostly compare more than termination, sometimes resulting in loos- one character and use the dichotomous ing visibility of some important characters. approach in the identification line. A draw- On the other hand, the importance of chi- ing is only given, when it was not possible Introduction 5 In freshwater ecosystems, chironomids are visible characters such as head coloura- frequently the dominant component both tion, body hairs, body colouration, and in total biomass and in total species diver- shape, as a series of taxa can be identified sity. Thus, the species observed in the field by certain striking macroscopic features. reflect to a large extent the complexity Frequently, the use of a microsope is help- and quality of habitats and life conditions. ful and necessary, even if an extensive In a number of countries, they are part of preparation will not be essential. the biological assessment system and In this key, the subfamilies are not treated monitoring, e. g. for the implemetation of separately, as the cross over of characters the EC Water Framework Directive. of closely related subfamilies does not al- However, the identification of indicator ways allow strict definition of the groups. taxa reveals some problems, as the speci- Sometimes, the appearance of a certain mens are frequently small compared to character in a taxon is variable, e. g. the other macro-invertebrates. This volume central part of the mentum can have one will provide assistance in taxa determina- or two teeth, or it appears so (e. g. due to tion, especially for beginners and those tooth wear from feeding). In such cases, who are not regularly concerned with this the identification line leads two different insect family. The keys include larval taxa ways, which converge again later or they from six subfamilies. For Tanypodinae, Val- terminate in two different places, but of lenduuk & Moller Pillot (2007) published a the same taxon. Using this method, the re- key using mainly macroscopic characters. sult of the determination can be im- Later, Orendt & Spies (2012) followed the proved. same approach for the Tribes Chironomini In this book, the larvae of 76 genera from and Pseudochironomini of the subfamily six subfamilies are included: Buchono- Chironominae. Here, this concept is con- myiinae (1 genus), Podonominae (3), Tel- tinued. The identification of genera and matogetoninae (2), Diamesinae (6), Prodi- species should be performed as far as pos- amesinae (3), and Orthocladiinae (61). 12 sible based on macroscopic characters us- more genera restricted to the northern ing photographs, tables, and adJacent text. and eastern parts of Europe according to However, the characters of many of the Fauna Europaea are not included. But for species and genera of the Orthocladiinae the other regions of Europe, at least the and the other subfamilies are not as easy identification of genera should be possi- to observe as in the Chironomini. Often, ble, as far as known to date. In 9 genera, the smaller body size requires higher opti- the larval stage is not known. For selected cal resolution in order to examine the genera (apart from monospecific genera), characters properly. This makes it more some larvae can be identified to species important to focus on existing typical and group and species level. In order to avoid 6 misidentifications, only those larvae were not all users will have the earlier work included, which were treated by various mentioned above and thus will not be able authors and which can be separated from to consult it. each other with certainty. However, it should be understood that in many genera Equipment needed more species are recorded and described To examine your material with regard to from the adult stage than are known from the morphological characters used in the the larval stage. Thus, larval types found keys you will need a dissecting scope with with the identification line may represent up to 75 x magnification, as well as a com- more species than are know today. In spite pound microscope with up to 400 x mag- of this restriction, taxa included in the key nification. Using higher magnifications on can be reliably identified. a dissecting scope generally does not pro- This work mainly utilizes the experience vide better viewing, as it exceeds the phys- and knowledge of existing keys by Ander- ical limits of optical resolution. sen et al. (2013), Biró (1988), Cranston For examinations under the compound (1982), HirvenoJa (1973), Janecek (2007), scope you will need microscope slides Moller Pillot (2009), Schmid (1993), vari- (with or without a central depression), ous special publications, and our own ob- cover slips, alcohol or water as the me- servations. The notes on the habitats refer dium for observation, fine forceps, and at in general to Andersen et al. (2013), least one very fine dissecting needle. The- Janecek (2007), and Moller Pillot (2013), se equipment requirements do not exceed and also own observations. Apart from those required for determinations of other many original photographs, collegues