Diversity of bacterial endosymbionts and bacteria–host co‐evolution in G ondwanan relict moss bugs ( H emiptera: C oleorrhyncha: P eloridiidae)

Abstract

Summary Many hemipterans are associated with symbiotic bacteria, which are usually found intracellularly in specific bacteriomes. In this study, we provide the first molecular identification of the bacteriome‐associated, obligate endosymbiont in a G ondwanan relict insect taxon, the moss bugs ( H emiptera: C oleorrhyncha: P eloridiidae), which represents one of the oldest lineages within the H emiptera. Endosymbiotic associations of fifteen species of the family were analysed, covering representatives from S outh A merica, A ustralia/ T asmania and N ew Z ealand. Phylogenetic analysis based on four kilobases of 16 S –23 S r RNA gene fragments showed that the obligate endosymbiont of P eloridiidae constitute a so far unknown group of G ammaproteobacteria which is named here ‘ Candidatus Evansia muelleri’. They are related to the sternorrhynchous endosymbionts C andidatus P ortiera and C andidatus C arsonella. Comparison of the primary‐endosymbiont and host ( COI + 28 S rRNA ) trees showed overall congruence indicating co‐speciation the hosts and their symbionts. The distribution of the endosymbiont within the insect body and its transmission was studied using FISH . The endosymbionts were detected endocellularly in a pair of bacteriomes as well as in the ‘symbiont ball’ of the posterior pole of each developing oocyte. Furthermore, ultrastructural analysis of the M alpighian tubules revealed that most host nuclei are infected by an endosymbiotic, intranuclear bacterium that was determined as an A lphaproteobacterium of the genus R ickettsia .

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