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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 7479

Eric W. Linton, Dana Hittner, Carole Lewandowski, Theresa Auld, and Richard E. Triemer; A Molecular Study of Euglenoid Phylogeny using Small Subunit rDNA. J.Eukaryot.Microbiol. 46(2):217-223, 1999

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The euglenoids are an ancient and extremely diverse lineage of eukaryotic flagellates with unclear relatonships among taxa. Synapomorphies for the euglenoids include a suface pellicle and a closed mitosis with a series of separate sub-spindles. The taxonomy currently in use is inconsistent with the available data and needs revison. Most euglenoid phylogenies are largely intuitive reconstructions based on a limited number of morphological characters. Therefore, we have added molecular characters from the Small Subunit (SSU) rDNA to generate an overall phylogenetic framework for the euglenoids. SSU rDNA sequences from photoshynthetic, osmotrophic, and phagotrophic euglenoids were alinged based on secondary structure. Phylogenetic analysis using the conserved areas of the sequence was perfomed using parsimony, maximum likelihood, and distance methods. Trees derived using different criteria are in agreement. The euglenoids form a distinct monophyletic clade with phagotrophic members diverging prior to the phototrophic and osmotrophic members. Among the photosynthetic members, the biflagellate form diverged prior to the uniflagellate form. Additionally, the genus Euglena appears to be paraphyletic, with osmotrophic taxa, such as Astasia and Khawkinea, diverging independently within the clade containing the photosynthetic genus Euglena.