A summary of the database pertaining to the phylogeny of the major groups of parasitic platyhelminths, with a revised classification

Abstract

A previously published phylogenetic systematic analysis of the major groups of parasitic platyhelminths was based on 39 anatomical characters. The resulting phylogenetic tree had a consistency index, which indicates the degree of fit of the data to the tree hypothesis, of 95% due to two postulated cases of convergence. That tree is evaluated in light of 49 additional anatomical characters and 32 ultrastructural characters. The additional anatomical characters support the original hypothesis with a consistency index of 100%, indicating no additional convergence in the data. The total anatomical database has a consistency index of 97.8%. The ultrastructural characters provide a best fit to a phylogenetic tree of 94.1 %, due to two postulated cases of convergent evolution. That tree is the same as the one supported by the anatomical data. The combined database thus comprises 120 characters having a consistency index of 96.7%, due to four postulated cases of convergent evolution. A classification of the major groups of parasitic platyhelminths is proposed, and represents a compromise between two earlier proposed schemes.