The adults and preimaginal stages of Cricotopus (C.) beckeri Hirv. from northwestern Africa and south west of France are described. Some comments about the systematic position, ecology and distribution are given. Les adultes et les stades preimaginaux des populations continentales de Cricotopus (Cricotopus) beckeri Hirvenoja (Diptera, Chironomidae).
The emergence of the marine species Halocladius variabilis (Staeger) in the surroundings of theTvärminne Biological Station (about 6‰S) in the northernBaltic Sea in 1952–1953 is outlined. Most individuals emerged in the submerged funnel traps used in the study from the last half of May to the end of June. The population density in the sites studied varied between 0 and 328 indiv./m2; wide areas had a population density of nearly 10 indiv./m2. No emergence was found in the traps nearest to the buildings of the station, but the highest numbers of the emergence occurred in the most distant sites studied.
The karyotype, morphology of adult, pupae and larvae, and the ecology of Glyptotendipes aequalis Kieffer (1922) are described from material from Finland, and a neotype from the (probably) original German material is designated. 2n = 8. Ist, IInd and IIIrd chromosomes are metacentric, IVth acrocentric. The IVth chromosome has a nucleolus and a Balbiani ring. G. aequalis is karyologically closely related to G. caulicola, differing by a simple inversion step.
Based on pupal exuviae, two sympatric pupal forms of Chironomus plumosus auctt. are present in the museum materials collected in 1952–1962 from the brackish water near the Tvärminne Biological Station at the northern Baltic Sea. The predominating undescribed type of the pupal exuviae is called here the “Balticmarine species” (possible C. plumosus sensu Linnaeus; direct observations by Linnaeus of Tipula plumosa from freshwater are not on record). Its pupal exuviae and the associated female and male from the Tvärminne population are described. Attempts to find larvae of the genus Chironomus in the sea area of Tvärminne for the renewed and more complete studies failed during the 1980s and 1990s. Only two larvae of the undescribed species of the karyological Chironomus plumosus group were captured. The possible reasons for the supposedly changed environmental conditions are discussed.
A detailed description of the karyotype of Chironomus jonmartini Lindeberg as well as data for its polymorphism are presented. The polymorphism is realized by heterozygous inversions and a high percentage of additional "B", chromosomes. Males, females, pupae and larvae are also redescribed. C. jonmartini is compared morphologically with a karyologically unidentified species of the genus Chironomus, the males of which are to a certain extent similar to it.
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