endosymbiont - Robuta Search

https://www.merriam-webster.com/dictionary/endosymbiont

The meaning of ENDOSYMBIOSIS is symbiosis in which a symbiont dwells within the body of its symbiotic partner.

https://www.semanticscholar.org/topic/Wolbachia-endosymbiont-of-Leptogenys-oswaldi/10970210

https://www.endosymbiont.com/celltypes/mast-cells