Sodalis praecaptivus subsp. spalangiae subsp. nov., a nascent bacterial endosymbiont isolated from the parasitoid wasp, Spalangia cameroni

An endosymbiotic bacterium of the genus Sodalis, designated as strain HZ^T, was cultured from the parasitoid wasp Spalangia cameroni, which develops on the pupae of various host flies. The bacterium was detected in S. cameroni developed on houseflies, Musca domestica, in a poultry facility in Hazon, northern Israel. After culturing, this bacterium displayed no surface motility on Luria–Bertani agar and was rod-shaped and irregular in size, ~10–30 nm in diameter and 5–20 µm in length. Phylogenetic analyses revealed that strain HZ^T is closely related to Sodalis praecaptivus strain HS^T, a free-living species of the genus Sodalis that includes many insect endosymbionts. Although these bacteria maintain >98% sequence identity in shared genes, genomic characterization revealed that strain HZ^T has undergone substantial reductive evolution, such that it lacks many gene functions that are maintained in S. praecaptivus strain HS^T. Based on the results of phylogenetic, genomic and chemotaxonomic analyses, we propose that this endosymbiont should be classified in a new subspecies as S. praecaptivus subsp. spalangiae subsp. nov. The type strain for this new subspecies is HZ^T (=ATCC TSD-398^T=NCIMB 15482^T). The subspecies Sodalis praecaptivus subsp. praecaptivus strain HS^T is created automatically with the type strain ATCC BAA-2554^T (=DSMZ 27494^T).