Taxonomic Revision of Diatoms belonging to the family Naviculaceae based on morphological and molecular data.

Based on morphology, the taxonomy of the family Naviculaceae (sensu Krammer&Lange-Bertalot, 1986) has been highly changed (e.g., Round et al., 1990), but little work has been carried out with molecular data for this large and ecologically important group of diatoms. My thesis was aimed at the investigation of evolutionary relationships within the naviculoid pennates using molecular and morphological data. Phylogenies based on sequences of the nuclear-encoded SSU rRNA gene, the LSU rRNA gene, the chloroplast rbcL gene and a combined dataset were compared. This study confirms the assumption that the genus Navicula sensu lato is a very heterogenous group and my results support the monophyly of Navicula sensu stricto. Several 'Navicula' species, which do not belong to the section Lineolatae could be recombined. The monophyly of several genera could be supported. But the actual differentiation of the genera Caloneis and Pinnularia is rejected. The separation of the subgenus Halamphora from the genus Amphora is supported by molecular and morphological data. This study also resolve several relationships between different genera.