Localization and morphological variation of three bacteriome-inhabiting symbionts within a planthopper of the genus Oliarus (Hemiptera: Cixiidae)

Many planthoppers of the family Cixiidae (Hemiptera: Fulgoroidea) host three bacteriome-inhabiting bacteria: a gammaproteobacterium: Ca.Purcelliella pentastirinorum', a betaproteobacterium: Ca. Vidania fulgoroidea', and a member of the bacteroidetes: Ca.Sulcia muelleri'. Through light microscopy observations, DGGE PCR and FISH analysis, we examined the morphology and localization of these three endosymbionts within the abdomens of females of the planthopper Oliarus filicicola. Our results indicate a complex distribution and variation in bacterial morphologies. Ca.Sulcia muelleri' singularly colonize one pair of bacteriomes and have cells of irregular shape with an average diameter of approximately 4-5m. Ca.Purcelliella pentastirinorum' bacteria are roughly globular and have an average diameter of approximately 1.5-2m in a pair of bacteriomes located near the posterior end of the abdomen, which are surrounded by giant and highly degenerated cells of Ca.Vidania fulgoroidea'. In addition, Ca.Vidania fulgoroidea' colonizes the rectal organ' (sensuBuchner) and the bacterial cells appear as a small, roughly globular with an average diameter of 3m; whereas, Ca.Purcelliella pentastirinorum' infects an additional two bacteriomes and the bacterial cells appear tightly packed and highly degenerated. All three endosymbionts colocalize in the forming eggs inside the host's ovaries. Based on the abdominal distribution of bacteriomes and bacterial morphologies, we suggest that Ca.Vidania fulgoroidea' and Ca.Purcelliella pentastirinorum' correspond to the symbionts described by Buchner as the x-' and the c+d symbiont' respectively.