1 Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Faculty of Science, University of South Bohemia, České Budějovice (Budweis), Czech Republic.
2 Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice (Budweis), Czech Republic; Faculty of Science, Charles University, Prague, Czech Republic.
3 Faculty of Environmental Sciences, Czech University of Life Sciences, Prague, Czech Republic. Electronic address: o.balvin@centrum.cz.