title: Cryptic diversity of free-living parabasalids, Pseudotrichomonas keilini and Lacusteria cypriaca n. g., n. sp., as inferred from small subunit rDNA sequences.
abstract: Ultrastructural and molecular phylogenetic evidence indicate that the Parabasalia consists of seven main subgroups: the Trichomonadida, Honigbergiellida, Hypotrichomonadida, Tritrichomonadida, Cristamonadida, Spirotrichonymphida, and Trichonymphida. Only five species of free-living parabasalids are known: Monotrichomonas carabina, Ditrichomonas honigbergii, Honigbergiella sp., Tetratrichomonas undula, and Pseudotrichomonas keilini. Phylogenetic analyses show that free-living species do not form a clade and instead branch in several different positions within the context of their parasitic relatives. Because the diversity of free-living parabasalids is poorly understood, the systematics of these lineages is in a significant state of disarray. In order to better understand the phylogenetic distribution of free-living parabasalids, we sequenced the small subunit rDNA from three different strains reminiscent of P. keilini; the strains were isolated from different geographical locations: (1) mangrove sediments in Japan and (2) sediments in Cyprus. These data demonstrated that the free-living parabasalids P. keilini and Lacusteria cypriaca n. g., n. sp., form a paraphyletic assemblage near the origin of a clade consisting mostly of parasitic trichomonadids (e.g. Trichomonas vaginalis). This paraphyletic distribution of similar morphotypes indicates that free-living trichomonadids represent a compelling example of morphostasis that provides insight into the suite of features present in the most recent free-living ancestor of their parasitic relatives.
authors.affiliation: Department of Botany, Canadian Institute for Advanced Research, Program in Integrated Microbial Biodiversity, University of British Columbia, Vancouver, British Columbia, Canada. yubuki@interchange.ubc.ca
authors.forename: Naoji
authors.initials: N
authors.lastname: Yubuki
authors.forename: Vít
authors.initials: V
authors.lastname: Céza
authors.forename: Ivan
authors.initials: I
authors.lastname: Cepicka
authors.forename: Akinori
authors.initials: A
authors.lastname: Yabuki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Inagaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakayama
authors.forename: Isao
authors.initials: I
authors.lastname: Inouye
authors.forename: Brian S
authors.initials: BS
authors.lastname: Leander
mesh_terms: D016000:Cluster Analysis; D003535:Cyprus; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D004783:Environmental Microbiology; D020459:Genes, rRNA; D007564:Japan; D008969:Molecular Sequence Data; D056900:Parabasalidea / Q000145:classification* / Q000235:genetics*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D016053:RNA, Protozoan / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D016053:RNA, Protozoan; D012337:RNA, Ribosomal, 18S