Among endosymbiotic bacterial lineages, few are as intensely studied as
Rickettsiales
, which include the causative agents of spotted fever, typhus, and anaplasmosis. However, an important subgroup called “
Candidatus
Midichloriaceae” receives little attention despite accounting for a third of the diversity of
Rickettsiales
and harboring a wide range of bacteria with unique features, like the ability to infect mitochondria.