Cryptic diversity of free-living parabasalids, Pseudotrichomonas keilini and Lacusteria cypriaca n. g., n. sp., as inferred from small subunit rDNA sequences.
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.
Yubuki
Naoji
N
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
Céza
Vít
V
Cepicka
Ivan
I
Yabuki
Akinori
A
Inagaki
Yuji
Y
Nakayama
Takeshi
T
Inouye
Isao
I
Leander
Brian S
BS
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
D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D016053:RNA, Protozoan; D012337:RNA, Ribosomal, 18S