Phylogenetic position of Dysteria derouxi (Ciliophora: Phyllo-pharyngea: Dysteriida) inferred from the small subunit ribosomal RNA gene sequence

The complete small subunit rRNA (SSrRNA) gene sequence of a marine ciliate,Dysteria derouxi Gong and Song,2004,was determined to be of 1 708 nucleotides.The phylogenetic position of this species within the class Phyllopharyngea was deduced using distance matrix,maximum parsimony and maximum likelihood methods.Dysteria derouxi,together with other available ciliates of the class Phyllopharyngea,forms a monophyletic clade with strong bootstrap support in the distance matrix,maximum parsimony and likelihood tree construction methods,while the dysterids are,as a monophyletic group,phylogenetically close to the clade of chlamydodontids[values of 100% LS(least-squares),100% NJ(neighbor-joining)].In addition,the trees indicate that dysteriids may be a higher or specialized group within the class,which corresponds well to the morphology and infraciliature.