Myriapod monophyly and relationships among myriapod classes based on nearly complete 28S and 18S rDNA sequences.

Myriapods play a pivotal position in the arthropod phylogenetic tree. The monophyly of Myriapoda and its internal relationships have been difficult to resolve. This study combined nearly complete 28S and 18S ribosomal RNA gene sequences (3,826 nt in total) to estimate the phylogenetic position of Myriapoda and phylogenetic relationships among four myriapod classes. Our data set consists of six new myriapod sequences and homologous sequences for 18 additional species available in GenBank. Among the six new myriapod sequences, those of the one pauropod and two symphylans are very important additions because they were such difficult taxa to classify in past molecular-phylogenetic studies. Phylogenetic trees were constructed with maximum parsimony, maximum likelihood, and Bayesian analyses. All methods yielded moderate to strong support for the monophyly of Myriapoda. Symphyla grouped strongly with Pauropoda under all analytical conditions. The KH test rejected the traditional view of Dignatha and Progoneata, and the topology obtained here, though not significantly supported, was Diplopoda versus ((Symphyla + Pauropoda) + Chilopoda).