Evolution of the secondary symbiont Candidatus Serratia symbiotica in aphid species of the subfamily Lachninae

Buchnera aphidicola BCc, the primary endosymbiont of the aphid Cinara cedri (subfamily Lachninae), is losing its symbiotic capacity and might be replaced by the coresident Candidatus Serratia symbiotica. Phylogenetic and morphological analyses within the subfamily Lachninae indicate two different Ca. Serratia symbiotica lineages and support the longtime coevolution of both symbionts in C. cedri.