PHYLOGENETIC POSITION OF THE 2 UNCULTIVATED TRICHOMONADS PENTATRICHOMONOIDES SCROA KIRBY AND METADEVESCOVINA-EXTRANEA KIRBY FROM THE HINDGUT OF THE TERMITE MASTOTERMES DARWINIENSIS FROGGATT

The phylogenetic position of the two uncultivated trichomonad flagella tes Pentatrichomonoides scroa and Metadevescovina extranea symbiotic i n the hindgut of the Australian termite Mastotermes darwiniensis was d etermined by analysis of small subunit ribosomal DNA (SSU rDNA) sequen ces. After enrichment of the two trichmonads from crude hindgut conten ts and isolation of DNA the SSU rDNA was amplified by the polymerase c hain reaction (PCR). The amplification products were cloned and sequen ced resulting in two different sequences. Excluding the amplification primers the sequences were 1526 and 1500 nucleotides in length, respec tively. The two sequences were assigned to the corresponding flagellat e cells by whole cell hybridization using specific oligonucleotide pro bes. The SSU rDNA of Pentatrichomonoides scroa showed 87.3% similarity to Metadevescovina extranea and 87.2% and 93.0% to the other so far e xamined trichomonads Tritrichomonas foetus and Trichomitus trypanoides , respectively. Metadevescovina extranea was 89.0% and 88.1% similar t o Tritrichomonas foetus and Trichomitus trypanoides, respectively. The sequences were phylogenetically analysed using distance matrix and ch aracter state methods. Within the trichomonads Pentatrichomonoides sa oa and Trichomitus trypanoides clustered together in all analyses and Tritrichomonas foetus was the first branching trichomonad. Depending o n the data set used, the trichomonad cluster consisting of four SSU rD NA sequences was one of the three deepest branching eukaryotic lineage s.