Discovery of a new Wolbachia supergroup in cave spider species and the lateral transfer of phage WO among distant hosts

•A novel Wolbachia supergroup R is discovered in Telema cave spiders, which expands our knowledge of Wolbachia diversity.•Phage WO is present in supergroup R Wolbachia strains and has been horizontally transferred between far distant Wolbachia supergroups of A and R.•The infection rates of Wolbachia and phage WO are 100%, which arouses us to explore their roles to spider hosts.

Wolbachia are widespread intracellular bacteria infecting the major classes of arthropods and some filarial nematodes. In arthropods, Wolbachia have evolved various intriguing reproductive manipulations, including cytoplasmic incompatibility, parthenogenesis, feminization, and male killing. Sixteen supergroups of Wolbachia have been identified, named A–Q (except G). Though Wolbachia present great diversity in arthropods, spiders, especially cave spiders, are still a poorly surveyed group of Wolbachia hosts. Here, we report a novel Wolbachia supergroup from nine Telema cave spiders (Araneae: Telemidae) based on five molecular markers (16S rRNA, ftsZ, gltA, groEL, and coxA). In addition, phage WO, which was previously reported only in Wolbachia supergroups A, B, and F, infects this new Wolbachia supergroup. We detected a 100% infection rate for phage WO and Wolbachia in Telema species. The phylogenetic trees of phage WO and Wolbachia are not congruent, which suggests that horizontal transfer of phage WO has occurred in these secluded species. Additionally, these data indicate Telema–Wolbachia-phage WO may be a good model for exploring the horizontal transfer history of WO among different host species.