Phylogenetic analysis and systematization of post-paleozoic charophytes

Abstract

Based upon the principles of phylogenetic systematics, a new system of postPaleozoic charophytes is presented. All post-Paleozoic charophytes can be grouped into Quinquespiralia. a monophylum characterized by the apomorphy "oosporangium composed of five spiral cells". Within Quinquespiralia, the monophyletic groups Nitellaceae (emend.), and Lamprothamnaceae (nov.), Characeae (emend.), Clavatoraceae and Raskyellaceae have split off from the paraphyletic stem lineages consisting of’Porochara" and "Feistiella" respectively. The proposed phylogenetic system gives preference to conservation of homology of the basal plate (simple plate/muItipartite plate) over homology of the apical morphology (apex rounded or flat/apical neck), the latter being considered convergent in several cases. Two phylogenetic hypotheses are proposed due to the lack of information concerning the basal plate of Paleozoic charophytes. If the simple plate represents the plesiomorphic state within Quinquespiralia (case considered more probable), a monophyletic group with multipartite plate can be recognized. This monophyletic group, named Polyplacata, includes Nitellaceae as a subordinate taxon. If phyletic sequencing is applied, Polyplacata are of the same systematic rank as Lamprothamnaceae, Characeae, Clavatoraceae and Raskyellaceae. The proposed phylogenetic system reflects the evolution of postPaleozoic charophytes much better than former classifications and allows one to recognize the paraphyly of Porocharaceae as well as the polyphyly of Characeae of traditional paleontological systematics. © 1991 Taylor and Francis Group, LLC.