On the taxonomic status of the intracellular bacterium Wolbachia pipientis: should this species name include the intracellular bacteria of filarial nematodes?

Lo et al. (2007) propose that all endobacteria of arthropods and nematodes commonly called Wolbachia be formally declared as Wolbachia pipientis. Part of their reasoning is based on the difficulty of assigning the strains to monophyletic species due to the lack of an appropriate outgroup and the fact that to name arthropod strains after the species they infect would be unwieldy because of the huge number of arthropod species infected with these endobacteria (Lo et al., 2007). This was the consensus reached at the 2004 international conference on W. pipientis (Heron Island, Australia, August 2004). However, in 2005, the genome of Wolbachia from the filarial nematode Brugia malayi (wBm) was published (Foster et al., 2005) and compared with the previously published genome of the Wolbachia from Drosophila melanogaster (wMel) (Wu et al., 2004). Analysis of the genome and the biology of the Wolbachia in nematodes argues against including these endobacteria with those from arthropods as W. pipientis.