Onishchuk I. The struсture of Octolasion tyrtaeum s. lato (Savigny, 1826) and Octodrilus transpadanus s. lato (Rosa, 1884) (Oligochaeta, Lumbricidae) earthworms species complexes on the territory of Ukraine: genetic, karyological and morphological peculiarities.

Octolasion tyrtaeum s. l. is established to be represented with at least 19 biotypes with different degree of genetic differentiation. In the Northern and Central Ukraine two geneticly polymorphic symbiotopic forms dominate, which differ in fractions of non-specific esterases. They are characterized with subtriploid set of chromosomes (2n+х=38) and anomalous spermatogenesis which goes on with chromosome number less than gaploid one, they also differ in size and some body proportions. In the South, according to kariological analysis of Crimean earthworms, only clone forms with triploid genome structure (3n=54) and some morphological peculiarities are established. Polyploid (4n, 7n) chromosome races of Оctodrilus transpadanus s. l., are found and the genetic structure of this species complex population is investigated. The continental population is represented with a series of clone and hypervariable biotypes. Tetraploid O. transpadanus (v. Mostove, Autonomous Republic of Crimea) are identified from continental biotypes with some species specific alleles and morphological peculiarities. The evolution of both species complexes karyotypes was accompanied with genome poliploidization which resulted in formation of poliploid series and transition from amphimictic reproduction to facultative and obligate parthenogenesis.