Maximum likelihood phylogram based on sequences of the COI mtDNA gene of selected polyopisthocotylan species. Newly sequenced isolates are in bold. Posterior probability followed by bootstrap support values are given next to the branches (posterior probability < 0.90 and bootstrap < 60 not shown). Plectanocotyle gurnardi (Van Beneden & Hesse, 1863) Llewellyn, 1941 was used as an outgroup. Branch length scale bar indicates number of substitutions per site.