Parasitism of one vertebrate host species by more than one parasite species belonging to the same genus is not a rare phenomenon in flatworms. However, in the composition of different taxa of cestodes and trematodes, most often there are no more than three species of the same genus confined to one vertebrate species. The microevolutionary mechanisms of the emergence of such groups of species in cestodes and trematodes, as a rule, remain unclear.
Scientists from the Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences (IEE RAS) in collaboration with colleagues from Russia, China and Japan studied the genetic diversity of cestodes of the genus Nippotaenia from the intestines of the Amur sleeper (Perccottus glenii), an invasive freshwater fish that has spread widely in many countries of Europe and the Asian part of our country over the past hundred years. The results of studying two DNA loci indicate the possible existence of five species of these parasites associated with this host. This study does not confirm the current taxonomic concept of parasitism of the Amur sleeper by a single species of Nippotaenia. To date, the putative species have been characterized only at the molecular level.
"Obtaining morphological evidence of the species isolation of these cestodes is a matter for the future. All five putative species were found in the Amur sleeper within the native part of its range. “Only two Nippotaenia species have been recorded in the acquired part of the fish range, one of which has only a local distribution,” said Sergey Sokolov, Senior Researcher at the Institute of Ecology and Evolution of the Russian Academy of Sciences.
Identification of the genetic diversity of Nippotaenia opens up additional opportunities for studying the routes of the Amur sleeper introduction.
The results of the study were published in the journal Hydrobiologia (SJR, Q1): Sokolov, S.G., Vlasenko, P.G., Urabe, M Atopkin. D.M., Reshetnikov, A.N., Yang, P., Izotova, G.V., Shedko, M.B. & Solovyev, M.M. 2025. Hidden diversity of cestode Nippotaenia in a widely distributed invasive fish Perccottus glenii. Hydrobiologia 852, 1903–1920.