RIBOSOMAL-RNA SEQUENCE COMPARISONS DEMONSTRATE AN EVOLUTIONARY RELATIONSHIP BETWEEN ZYGNEMATALES AND CHAROPHYTES

The nuclear-encoded small subunit ribosomal RNA (rRNA) sequences were determined for Genicularia spirotaenia, Mesotaenium caldariorum, and S taurastrum spec. (Zygnematales) to elucidate the evolutionary position of these green algae. Results of neighbour-joining and maximum parsim ony phylogenetic analyses support a monophyletic origin of the Zygnema tales within the evolutionary assemblage defined by the Charophyceae ( sensu MATTOX & STEWART) and land plants. The Zygnematales/Charophyceae /land plants are evolutionarily distinct from the monophyletic lineage defined by the Chlorodendrales, Pseudoscourfieldiales, and the Microt hamniales/Chlorophyceae.