tardiphaga robiniae tardiphaga robiniae tardiphaga robiniae is a gram-negative and rod-shaped bacteria from the family of tardiphaga which has been isolated from robinia pseudoacacia root nodules. tardiphaga robiniae scientific classification domain: bacteria phylum: pseudomonadota class: alphaproteobacteria order: hyphomicrobiales family: nitrobacteraceae genus: tardiphaga species: t. robiniae binomial name tardiphaga robiniaecai et al. 2011