Genealogical relationships of haplotypes of the cox1 gene of specimens of Heterosentis holospinus and specimens of Class Palaeacanthocephala recovered in a maximum likelihood analysis (L_n = −11,079.294). Support values, only given for species and multispecies clades, correspond to SH-aLRT test and ultrabootstrap proportions. The number below the internal nodes shows ML bootstrap support values. The clades with different colors, Echinorhynchidae (red), Cavisomidae (green), and Rhadinorhynchidae (blue) indicate a paraphyletic arrangement. GenBank accession numbers are also given at the terminal labels and bolded names were generated in this study.