FRESH-WATER GOMPHONEMOID DIATOM PHYLOGENY - PRELIMINARY-RESULTS

A cladistic analysis of eleven freshwater gomphonemoid diatom taxa yie lded three equally most parsimonious cladograms. The three cladograms suggest Gomphoneis Cleve is non-monophyletic as originally and recentl y circumscribed. Gomphoneis elegans and G. transsilvanica (Pant.) Kram mer are more closely related to Gomphopleura Reichelt ex Tempere than to other members of the genus. Gomphoneis geitleri Kociolek and Stoerm er appears to represent a monotypic lineage. Among the taxa with diffe rentiated apical pore fields Gomphonema kaznakowi Mereschkowsky appear s to be primitively astigmate. The three cladograms vary with regard t o systematic affinities among the Gomphoneis herculeana (Ehrenberg) Cl eve group, Miocene gomphonemoid species from Idaho (USA), gomphonemoid taxa from East Africa and Gomphonema sensu stricto. Despite variabili ty in number of puncta rows per stria and presence of an axial plate i n the Miocene species from North America, inclusion of these taxa in t he analysis provided better resolution of relationships than if they w ere excluded.