Chromosomal Variability in Chironomus plumosus (Linnaeus, 1758) (Diptera, Chironomidae) from a Coastal Lagoon of the Baltic Sea (Curonian Lagoon)

Chromosomal variability of Chironomus plumosus (Linnaeus, 1758) population from the coastal Curonian Lagoon of the Baltic Sea was studied. The karyotype pool comprises 19 banding sequences (exceeding the mean value of 12.5 ± 0.4 sequences for the Palaearctic populations) and includes some unique sequences that are described here for the first time for the species: p'pluB15, p'pluB16, p'pluC7, p'pluD19, p'pluE3, and p'pluF7. The latter four banding sequences have resulted from pericentric inversions which are rare in Ch. plumosus . Altogether, 21 zygotic and 19 genomic combinations of banding sequences were found. The indices of chromosomal variability, i.e., the proportion of heterozygous individuals (54.43 ± 7.08%) and the number of heterozygous inversions per individual (0.71 ± 0.10), were lower than those in the center of the Palaearctic part of the species’ range; this is typical of peripheral populations. The structure of chromosomal variability has been stable throughout the entire study period (1975, 1998–2009), probably due to favorable living conditions in the Curonian Lagoon.