Chromosomes, morphology, ecology and distribution of Sergentia baueri, spec. nov v S. prima Proviz & Proviz, 1997 and S. coracina Zett.,1824 (Insecta, Diptera, Chironomidae). W. Wülker, I. I. Kiknadze, I. E. Kerkis and P. Nevers Wülker, W., I. I. Kiknadze, I. E. Kerkis & P. Nevers (1999): Chromosomes, morphology, ecology and distribution of Sergentia baueri, spec. nov., S. prima Proviz & Proviz, 1997 and S. coracina Zett., 1824 (Insecta, Diptera, Chironomidae). -Spixiana 22/1: 69-81 1. As proposed earlier Sergentia longiventris Kieffer is a junior synonym for S. coracina. Therefore the Sergentia material from the Black Forest, Alps (Lunzer Mittersee) and Far East represents a new species (2n=8), S. baueri. The Fennoscan-dian Sergentia with 2n=8 belongs to the species S. prima recently described in reservoir lakes of the Baikal area in Siberia. 2. The karyotype of these two species as well as that of S. coracina (2n=6) has been investigated. 3. Some morphological data for the species and keys for analysis of chromo-somes, larvae, pupae and male adults are provided. 4. Sergentia baueri only occurs in small, considerably eutrophied pools. S. prima prefers (in Scandinavia) shallow humous to polyhumous lakes, while S. coracina prefers deep, sometimes ultraoligotrophic lakes. Nevertheless Joint occurrence of S. prima and S. coracina is observed in Norvegian lakes. S. prima and S. baueri coexist in the Irkutsk reservoir in Siberia. 5. Sergentia baueri extends from West Germany to the Far East of Russia; S. prima has been described from Siberia and Fennoscandia; S. coracina is holarctic. Prof. Dr. W. Wülker, Institut für Biologie (Zoologie) der Universität, Haupt-straße 1, D-79104 Freiburg im Breisgau, Germany. Prof. Dr. I. I. Kiknadze, Dr. I. E. Kerkis, Institute of Cytology and Genetics, Siberian Branch Russian Academy Sciences, Prosp. Akademika Lawrentieva 10, 630090 Novosibirsk, Russia. Prof. Dr. P. Nevers, Universität Hamburg, Fachbereich Erziehungswissenschaft, Von Meile-Park 8 D-20146 Hamburg, Germany. Introduction The genus Sergentia is important as an indicator of "mesotrophic" conditions in freshwater lakes (Lenz 1925,1927). Two species in particular are well known in Europe: S. Coracina Zetterstedt is an apparently cold stenothermic but euryoxybiontic species that inhabits fairly deep lakes. It occurs not only in Europe (for a summary of data see Brundin 1949) but also in the USA and Canada (Johannsen 1934, Townes 1945, Stahl 1959, 1966). S. "longiventris" Kieffer was assumed to be present not only in Fennoscandia (Brundin 1949) but also in the Alps (Brehm 1942, Thienemann 1943, Bauer 1945), the Black Forest of Germany (Lundbeck 1951, Wülker 1961, Nevers 1972), and the USSR (Tschernovskij 1949, Linevich 1981, Proviz et al. 1991, Kiknadze et al.1991, and unpublished data of I. Kerkis and E. 69
Chromosomes, morphology, ecology and distribution of Sergentia baueri, spec. nov., S. prima Proviz & Proviz, 1997 and S. coracina Zett., 1824 (Insecta, Diptera, Chironomidae)
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