PHYLOGENY, NATURAL GROUPS AND NEMERTEAN CLASSIFICATION

Contemporary practice in the classification of nemerteans (phylum Neme rtea) is critically discussed. It is argued that basing higher taxa on the existence of a unique combination of characters in a species (or genus) is unlikely to lead to monophyletic taxa, and that this approac h should be abandoned in favour of a classification based on explicit hypotheses of phylogeny. These hypotheses should be based on all avail able characters and characters should not be excluded before the analy sis. The classification should be based on a reconstruction of the phy logeny and reflect this phylogeny in an unambiquous way.