Morphology and karyotypes of three sympatric species of the genus Chironomus (Chironomidae, Diptera) from Trans-polar region

Three new sympatric species of the genus Chironomus (C. frequentatus sp.n., C. laetus sp.n., C. borealis sp.n.) from the trans-polar region are described. Males of these species are identified by the form, size of hypopyge and upper appendages. Females are identified by the form of hills of VIII sternite, laterosternites, sclerites of X tergite. Pupae are differed in pigmentation of exuviae, structure of the thorn top in the VIII tergite back corner. C. borealis larvae are easily identified by the colour of frontal sclerite and the forth lateral tooth of mentum which is lower than the adjacent teeth. C. frequentatus and C. laetus are similar in pigmentation and morphometry of head capsules, but C. laetus as opposed to C. frequentatus does not have lateral appendices. In all three species 2n-8. By combination of chromosome arms AB, CD, EF, G, the species are referred to the cytocomplex thummi. In C. laetus any chromosome reconstructions are not found. In C. borealis and C. frequentatus any inversions are very rare.