Contributions to the taxonomy and ecology of the <i>Chironomus plumosus</i> sibling species aggregate (Diptera: Chironomidae): the brackish water populations of Tvärminne area, Finland

Hirvenoja, M. 2006: Contributions to the taxonomy and ecology of the Chironomus plumosus sibling species aggregate (Diptera: Chironomidae): the brackish water populations of Tvarminne area, Finland — Entomol. Fennica 17: 373– 380. 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 Tvarminne Biological Station at the northern Baltic Sea. Thepredominatingundescribedtypeofthepupalexuviaeiscalledherethe“Balticmarinespecies”(possibleC.plumosussensuLinnaeus;directobservationsby LinnaeusofTipulaplumosafromfreshwaterarenotonrecord).Itspupalexuviae and the associated female and male from the Tvarminne population are described. Attempts to find larvae of the genus Chironomus in the sea area of Tvarminne for the renewed and more complete studies failed during the 1980s and1990s.OnlytwolarvaeoftheundescribedspeciesofthekaryologicalChironomus plumosus group were captured. The possible reasons for the supposedly changed environmental conditions are discussed.