Chironomus bonus Shilova & Dzhvarsheishvili

Michailova, Paraskeva, 2024, Markers in the polytene chromosomes of freshwater Chironomus Meigen (Diptera, Chironomidae) species, Zootaxa 5453 (4), pp. 511-537 : 518

Chironomus bonus Shilova & Dzhvarsheishvili

The chromosome set is 2n = 8.AB and CD chromosomes are metacentric, EF—submetacentric and G chromosome— telocentric. The centromeric regions are dark thin bands, well defined ( Fig. 6 ). A chromosome G has one NOR, near to the centromere and two BRs. The species is homosequential to Chironomus plumosus (Linnaeus) and distinguished by shape of its hypopygium (Michailova 1994). In Russian populations of the species, an additional B chromosome, characteristic of the genome of the species, was found ( Kiknadze et al. 2016; Petrova & Zhirov 2022), but in the studied Bulgarian population such an additional chromosome was not found. It is characteristic of the species that chromosome G has incomplete conjugation almost throughout the chromosome, only in the area of the NOR homologues have conjugated ( Fig. 6 ).In the middle of this chromosome there is a group of dark bands—makers of the species. Thirty-five larvae were examined.

Collection sites: Shabla Lake.

Figures

FIGURE 6. Polytene chromosomes of Chironomus bonus.The numbers on the chromosome arms indicate the “basic”sequences. The large arrows show the localization of the centromere region. The small arrow on chromosome G indicates the marker sequences required for species identification. BR—Balbiani Ring, NOR—Nuclear Organizer Region.A, B, C, D, E, F, G—arms of the chromosomes. Scale bar, 10µm.