The phylum Placozoa, represented by its single species Trichoplax adhaerens, has always been considered one of the most basal animal clades due to its low morphological complexity. However, despite its importance, the phylogenetic position of the Placozoa remains uncertain, as does the relationships between the basal metazoans. We sequenced the nearly complete large subunit (LSU) of the T. adhaerens rRNA gene together with the small subunit (SSU) rRNA and used several methods to infer the phylogenetic position of Placozoa and the relationships between the basal animal phyla. The phylogenetic trees obtained from the LSU, SSU and SSU + LSU datasets support monophyly of all basal metazoan phyla, except the Porifera. However, the relationships between all... |