show Abstracthide AbstractWithin the Lachninae subfamily of aphids, a putative ancient pseudogenisation of the riboflavin biosynthetic genes in the Lachninae's Buchnera last common ancestor rendered Buchnera unable to supply this essential nutrient to the aphid, and thus triggered the establishment of secondary co-obligate endosymbionts. Through co-occurrence data of same-haplotype secondary endosymbionts across different populations, we determined that Cinara cuneomaculata apparently harbours an Erwinia-related symbiont as Buchnera's co-obligate endosymbiont. Metabolic reconstruction of these endosymbionts, corroborates the co-obligate nature of these, particularly due to the putative riboflavin-provider role assumed by Erwinia-related symbiont