Monophyly and paraphyly: A discourse without end?

Abstract The ongoing discourse on monophyly versus paraphyly shows apparent lack of mutual understanding among schools of biological taxonomy. The principal reason behind the frozen disagreement is that these terms were redefined repeatedly. Although terminological discrepancy has long been recognized, relatively few attempts have been made to clarify this. As a consequence, contemporary taxonomy still uses three different definitions of monophyly, and therefore paraphyly. Resolution is possible provided that the terms (a) monophyly and paraphyly are used for diachronous classifications and phylogenetic trees; (b) monoclady and paraclady for synchronous classifications and cladograms of contemporaneous organisms; and (c) monothety and non‐monothety for groups in classifications derived by the pattern cladistic approach.