Hox gene sequences from the geophilomorph centipede Pachymerium ferrugineum (C. L. Koch, 1835) (Chilopoda: Geophilomorpha: Geophilidae): implications for the evolution of the Hox class genes of arthropods.

Here we report on a partial screen for Hox gene sequences from the geophilomorph centipede Pachymerium ferrugineum, resulting in 11 different sequences. All of these sequences could be homologized to specific Drosophila genes, yielding two representatives for the Dfd class and one each for the remaining classes. Phylogenetic analysis of these data with a broad sample of arthropod/onychophoran homologous sequences confirmed these results and provided further support for the monophyly of the Hox3/zen class. Conversely, the phylogenetic status of ftz-type genes remains uncertain. Our results complement the previous partial findings for two other centipedes (the scolopendromorph Ethmostigmus rubripes and the lithobiomorph Lithobius forficatus) and confirm the expectation that in myriapods, too, all Hox genes classes are present. This suggests that even the Chilopoda, with uniform trunk segments, have the same number of Hox genes as the more tagmatized Insecta.