Phylogeny and Systematic Position of Zosterodasys (Ciliophora, Synhymeniida): A Combined Analysis of Ciliate Relationships Using Morphological and Molecular Data |
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Authors: | K LINDHOLM KIVIMAKI BRUNELLA M BOWDITCH GAVIN P RIORDAN DIANA L LIPSCOMB |
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Institution: | Department of Biological Sciences, George Washington University, Washington, District of Columbia 20052;, and Department of Biology, Georgian Court University, Lakewood, New Jersey 08701 |
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Abstract: | ABSTRACT. The Synhymeniida is characterized both by a band of somatic dikinetids, the synhymenium, extending across the surface of the cell and by a ventral cell mouth lacking specialized feeding cilia but subtended by a well-developed cyrtos. The synhymeniids have been hypothesized to be members of the class Nassophorea but our previous ultrastructural study of the synhymeniid genus Zosterodasys did not show any clear synapomorphies that would permit definitive placement in the Nassophorea or as a sister taxon to any of the other ciliate groups possessing a cyrtos. In the present study, simultaneous analysis of morphological and small subunit rDNA molecular data indicates that the Synhymeniida are sister to the class Phyllopharyngea and that this clade is, in turn, sister to the remaining Nassophorea, although this result is sensitive to dataset inclusion and alignment parameters. While this suggests that taxa with a ventral cyrtos might be united into a named taxon (e.g. resurrecting the Hypostomata), additional data are needed to reach a definitive conclusion. |
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Keywords: | Direct optimization Nassophorea Phyllopharyngea phylogenetic analysis simultaneous analysis ssu-rDNA ultrastructure |
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