title: Molecular Evidence for the Polyphyly of Macrotrichomonas (Parabasalia: Cristamonadea) and a Proposal for Macrotrichomonoides n. gen.
abstract: Macrotrichomonas (Cristamonadea: Parabasalia) is an anaerobic, amitochondriate flagellate symbiont of termite hindguts. It is noteworthy for being large but not structurally complex compared with other large parabasalians, and for retaining a structure similar in appearance to the undulating membrane (UM) of small flagellates closely related to cristamonads, e.g. Tritrichomonas. Here, we have characterised the SSU rDNA from two species described as Macrotrichomonas: M. restis Kirby 1942 from Neotermes jouteli and M. lighti Connell 1932 from Paraneotermes simplicicornis. These species do not form a clade: M. lighti branches with previously characterised Macrotrichomonas sequences from Glyptotermes, while M. restis branches with the genus Metadevescovina. We examined the M. restis UM by light microscopy, scanning electron microscopy, and transmission electron microscopy, and we find common characteristics with the proximal portion of the robust recurrent flagellum of devescovinids. Altogether, we show the genus Macrotrichomonas to be polyphyletic and propose transferring M. restis to a new genus, Macrotrichomonoides. We also hypothesise that the macrotrichomonad body plan represents the ancestral state of cristamonads, from which other major forms evolved.
authors.affiliation: Department of Botany, Canadian Institute for Advanced Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Gillian H
authors.initials: GH
authors.lastname: Gile
authors.affiliation: Department of Botany, Canadian Institute for Advanced Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Erick R
authors.initials: ER
authors.lastname: James
authors.affiliation: Department of Botany, Canadian Institute for Advanced Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Noriko
authors.initials: N
authors.lastname: Okamoto
authors.affiliation: Department of Botany, Canadian Institute for Advanced Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Carpenter
authors.affiliation: University of Florida Research & Education Center, Davie, Florida, 33314, USA.
authors.forename: Rudolf H
authors.initials: RH
authors.lastname: Scheffrahn
authors.affiliation: Department of Botany, Canadian Institute for Advanced Research, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Keeling
mesh_terms: D000818:Animals; D016054:DNA, Protozoan / Q000235:genetics*; D004275:DNA, Ribosomal / Q000235:genetics; D020459:Genes, rRNA; D020049:Isoptera / Q000469:parasitology*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D056900:Parabasalidea / Q000145:classification* / Q000166:cytology / Q000235:genetics*; D010802:Phylogeny; D013559:Symbiosis
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal
keywords: Cresta; Neotermes; Paraneotermes; devescovinid; flagellate; termite; undulating membrane