How Oxymonads Lost Their Groove: An Ultrastructural Comparison of Monocercomonoides and Excavate Taxa
Despite being amongst the more familiar groups of heterotrophic flagellates, the evolutionary affinities of oxymonads remain poorly understood. A re-interpretation of the cytoskeleton of the oxymonad Monocercomonoides hausmanni suggests that this organism has a similar ultrastructural organisation t...
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Published in | The Journal of eukaryotic microbiology Vol. 49; no. 3; pp. 239 - 248 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Oxford, UK
Blackwell Publishing Ltd
01.05.2002
Blackwell |
Subjects | |
Online Access | Get full text |
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Summary: | Despite being amongst the more familiar groups of heterotrophic flagellates, the evolutionary affinities of oxymonads remain poorly understood. A re-interpretation of the cytoskeleton of the oxymonad Monocercomonoides hausmanni suggests that this organism has a similar ultrastructural organisation to members of the informal assemblage ‘excavate taxa’. The preaxostyle, ‘R1’ root, and ‘R2’ root of M. hausmanni are proposed to be homologous to the right, left, and anterior roots respectively of excavate taxa. The ‘paracrystalline’ portion of the preaxostyle, previously treated as unique to oxymonads, is proposed to be homologous to the I fibre of excavate taxa. Other non-microtubular fibres are identified that have both positional and substructural similarity to the distinctive B and C fibres of excavate taxa. A homologue to the ‘singlet root’, otherwise distinctive for excavate taxa, is also proposed. The preaxostyle and C fibre homologue in Monocercomonoides are most similar to the homologous structures in Trimastix, suggesting a particularly close relationship. This supports and extends recent molecular phylogenetic findings that Trimastix and oxymonads form a clade. We conclude that oxymonads have an excavate ancestry, and that the ‘excavate taxa’ sensu stricto form a paraphyletic assemblage. |
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Bibliography: | ark:/67375/WNG-FF72D7N6-S ArticleID:JEU239 istex:C9465E304BE4C1C9CDFCB03100B6AC9E10FB7D30 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 1066-5234 1550-7408 |
DOI: | 10.1111/j.1550-7408.2002.tb00529.x |