No abstract

Telomere elongation by telomerase is the most widespread mechanism among eukaryotes. However, alternative mechanisms such as homologous recombination between terminal satellite DNAs are probably used in lower dipteran insects and in some plants. Drosophila melanogaster uses the very unusual telomere elongation pathway of transposition of telomere-specific retrotransposable elements. The uniqueness of this telomere elongation mechanism raises the question of its origin. We, therefore, analyzed sequences located at telomeres of fairly distantly related Drosophila species, and in this paper we describe the characterization of complex satellite DNA sequences located at the telomeres of D. virilis and other species in the virilis group. We suggest an involvement of these DNA satellites in telomere elongation by homologous recombination similar to that found in lower dipterans. Our findings raise the possibility that telomere elongation by specific retrotransposons as found in D. melanogaster and its sibling species is a recent event in the evolution of dipteran insects.

The new species Epeorus (Caucasiron) bicolliculatus sp. nov. is described based on larvae and adults. Diagnostic characters are given with regard to the related species. The most pronounced difference is represented by protuberances on larval abdominal terga II-IX, present exclusively in E. (C.) bicolliculatus sp. nov. Primary data on the biology and distribution of the new species are also provided. Delimitation of the new species is verified by the analysis of COI (barcode) sequences. Barcode data for all Caucasian species of the subgenus Caucasiron are provided for the first time and compared with E. (C.) bicolliculatus sp. nov.