Nucleotide sequences of the D3 expansion segment of the 28S rDNA gene were used to reconstruct evolutionary relationships within the Adenophorea. Neighbor-joining and parsimony analyses of representatives of most major taxa revealed a paraphyletic Adenophorea (p = 0.0005). Within Adenophorea, the Enoplia, Enoplida, and Enoplina were paraphyletic (p = 0.0024, 0.0014, and 0.0120, respectively). A major division was evident within the Enoplida, with one lineage consisting of a basal Thoracostomopsidae and Enoplidae, and a second lineage consisting of Oncholaimidae and Encheliididae. Tripyloidina clustered close to the basal enoplid branch and formed a monophyletic taxon. Although appearing as paraphyletic in the maximum-parsimony and neighbor-joining trees,... |