ИСТИНА

Molecular phylogenetics has drastically reshaped our perception of macroevolutionary relationships among Nematoda during the last decade. Yet, detailed scenarios of the phylogenesis of major nematode lineages remained unreported. Here the authors communicate the milestone transitions in the phylogenesis of Chromadoria as reliably inferred from SSU rDNA sequence data. The analytic dataset included both sequences available from the GeneBank and originally obtained on some key chomadorian taxa. Phylogenetic analysis was conducted with the MCMC algorithm sampled over 10.000.000 generations. The phylogenesis of Chromadoria comprises several successive deviations, which can be assigned the order status in terms of the Linnaean classification. The basal lineages of Chromadoria consist of the order Chromadorida (including Cyatholaimidae, Selachinematidae, as well as genera Prodesmodora and Achromadora) and the order Desmodorida. More derived “higher” Chromadoria comprise a paraphyletic complex uniting conventional orders and families with outstretched ovaries, viz. Monhysterida (including Comesomatidae), Desmoscolecida, Linhomoeidae, and Araeolaimida sensu stricto with both outstretched and reflexed ovaries. Plectida (including Chronogaster and Aphanolaimus) and Teratocephalidae comprise the crown of Chromadorida along with Rhabditia (=Secernentea). Molecular evidence attests the paraphypy of Teratocephalidae. Genus Teratocephalus does not belong to Plectida and instead comprises an distinct sister group to Rhabditia.