The phylogenetic diversity of symbiotic bacteria in sucking lice suggests that lice have a complex history of symbiont acquisition, loss, and replacement throughout their evolution. These processes have resulted in the establishment of different, phylogenetically distant bacteria as obligate mutualists in different louse groups. By combining metagenomics and amplicon screening across several populations of three louse species (members of the genera Polyplax and Hoplopleura) we describe a novel louse symbiont lineage related to Neisseria and Snodgrassella, and show its independent origin in the two louse genera. While the genomes of these symbionts are highly similar, their respective distributions and status within lice microbiomes indicate that they have different functions and history. In Hoplopleura acanthopus, the Neisseriaceae-related bacterium is a dominant obligate symbiont present across several host populations. In contrast, the Polyplax microbiomes are dominated by the obligate symbiont Legionella polyplacis, with the Neisseriaceae-related bacterium co-occurring only in some samples and with much lower abundance. The results thus support the view that compared to other exclusively blood feeding insects, Anoplura possess a unique capacity to acquire symbionts from diverse groups of bacteria.
Keywords: amplicon sequencing; genome evolution; lice; microbiome; symbiosis.
© 2021 John Wiley & Sons Ltd.