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

Abstract

On the taxonomic status of the intracellular bacterium Wolbachia pipientis: should this species name include the intracellular bacteria of filarial nematodes? The recent article by Lo et al. (2007) aiming to recognize the Wolbachia endobacteria of arthropods and filarial nematodes as Wolbachia pipientis, while admirable for attempting to codify the nomenclature in this field of research, may not address the stark differences of the endobacteria found in nematodes compared with the endobacteria found in arthropods. 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.

Species in Wolbachia? Proposal for the designation of ‘Candidatus Wolbachia bourtzisii’, ‘Candidatus Wolbachia onchocercicola’, ‘Candidatus Wolbachia blaxteri’, ‘Candidatus Wolbachia brugii’, ‘Candidatus Wolbachia taylori’, ‘Candidatus Wolbachia collembolicola’ and ‘Candidatus Wolbachia multihospitum’ for the different species within Wolbachia supergroups

“…Our results support the previous proposal that Wolbachia from different supergroups should be considered as genetically distinct clades not only from implications related to host confinement and their biology [72], but on the basis of molecular evidence [30,53,78]. Furthermore, we found heterogeneity within supergroups.…”

Diversity and Phylogeny of Cardinium (Bacteroidetes) in Armored Scale Insects (Hemiptera: Diaspididae)

“…However, it must also be noted that the situation is complicated by the fact that the phylogenetic relationships within Cardinium are still confused and hence remain fluid (see Gruwell et al 2009;Nakamura et al 2009;Perlman et al 2010;discussed in Breeuwer et al 2012). To a certain extent, this problem also applies to reproductive parasites in general; for example, whether the far more intensively studied Wolbachia represents one or two species is still debated (Lo et al 2007;Pfarr et al 2007). This problem may be additionally compounded by general issues of false negatives inherent to PCR-based screening (see Breeuwer et al 2012), so overall, it is likely that frequency of infection with symbionts is being underestimated and novel bacteria are being missed (see e.g., Weinert et al 2007).…”

Prevalence of Cardinium Bacteria in Planthoppers and Spider Mites and Taxonomic Revision of “ Candidatus Cardinium hertigii” Based on Detection of a New Cardinium Group from Biting Midges

“…Considering the complex relationship and extensive recombination between various strains of Wolbachia, Lo et al (23) have argued for the single species Wolbachia pipientis. Conversely, Pfarr et al (33) claimed that Wolbachia should be divided into two species according to the host (arthropods versus filarial nematodes). In any case, a better understanding of their nature derived from further studies will allow more convincing classification of these symbionts.…”