title: Molecular phylogeny of parabasalids inferred from small subunit rRNA sequences, with emphasis on the Devescovinidae and Calonymphidae (Trichomonadea).
abstract: Small subunit rRNA sequences were obtained by polymerase chain reaction from trichomonad symbionts of termites that belong to the polymastigont Calonymphidae, including Snyderella tabogae, Calonympha grassii, and Metacoronympha senta. The yet-unidentified sequence Nk9 previously obtained from the termite Neotermes koshunensis, has also been shown to derive from the Devescovinidae Devescovina sp. by in situ hybridization. These new sequences were analyzed by distance, parsimony, and likelihood methods in a broad phylogeny including all identified parabasalid sequences available in databases. All analyses revealed the emergence of a very well supported Devescovinidae/Calonymphidae group but showed an unexpected dichotomy of the Calonymphidae represented by the "Coronympha" and "Calonympha" groups. It strongly suggests that the polymastigont state observed in the Calonymphidae might be explained by at least two independent evolutionary events. In a second phylogenetic analysis, some yet-unidentified parabasalid sequences likely deriving from the Devescovinidae/Calonymphidae taxa, were added to our data set. This analysis confirmed the polyphyly of the Calonymphidae. A tentative identification is proposed for each of these sequences, and hypotheses on the origin of the Devescovinidae and Calonymphidae are discussed. Tritrichomonas foetus or a close relative might be the best candidate for the ancestor of the Devescovinidae, fairly consistent with morphology-based hypotheses. Regarding the Calonymphidae, the origin of the "Coronympha" group might be found within the Devescovinidae, related to Foaina, whereas the "Calonympha" group may directly descend from Tritrichomonas or related species.
authors.affiliation: Laboratory of Microbiology, RIKEN (The Institute of Physical and Chemical Research), Wako, Saitama 351-0198, Japan.
authors.forename: Delphine
authors.initials: D
authors.lastname: Gerbod
authors.forename: Christophe
authors.initials: C
authors.lastname: Noël
authors.forename: Michael F
authors.initials: MF
authors.lastname: Dolan
authors.forename: Virginia P
authors.initials: VP
authors.lastname: Edgcomb
authors.forename: Osamu
authors.initials: O
authors.lastname: Kitade
authors.forename: Satoko
authors.initials: S
authors.lastname: Noda
authors.forename: Fabienne
authors.initials: F
authors.lastname: Dufernez
authors.forename: Moriya
authors.initials: M
authors.lastname: Ohkuma
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Kudo
authors.forename: Monique
authors.initials: M
authors.lastname: Capron
authors.forename: Mitchell L
authors.initials: ML
authors.lastname: Sogin
authors.forename: Eric
authors.initials: E
authors.lastname: Viscogliosi
mesh_terms: D000818:Animals; D003001:Cloning, Molecular; D004064:Digestive System / Q000378:metabolism; D017403:In Situ Hybridization; D016013:Likelihood Functions; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012335:RNA, Ribosomal / Q000235:genetics*; D017422:Sequence Analysis, DNA; D016834:Trichomonadida / Q000145:classification* / Q000235:genetics*
chemical_list: D012335:RNA, Ribosomal