Chironomus piger Strenzke

The chromosomes set of the species is 2n = 8. The chromosomes AB and CD are metacentric, the chromosome EF is submetacentric, the small chromosome G is telocentric (Fig.1). The centromeric regions of all chromosomes are dark bands, determined by the comparative analysis with the polytene chromosomes of the species presented by Kiknadze et al (2016). The “basic” sequences are located in the telomeres of the chromosome arms C, D, close to the telomeres of arms A and F and in the middle of arms B and E. Markers of the G chromosome are the Nuclear Organizer (NOR) and three Balbiani Rings (BRs) (BRa, BRb, BRc), as the BRa is not always expressed. NOR is located near the centromere separated from it by a dark band. The polytene chromosomes of the species were used to trace the impact of pollutants on the genomic characterization of the species by Ilkova et al. (2007). Seventy-three individuals were studied.

Collection sites: Sofia: Pancharevo Lake, Plovdiv: fish pool, Varna: small artificial pool, Burgas: near to Atanasovsko Lake .