Quatrionicoccus (also known as its synonym Quadricoccus) is a genus of gram-negative, oxidase-negative, catalase-positive, aerobic, non-spore-forming, non-motile bacteria from the family of Rhodocyclaceae which belongs to the class of Betaproteobacteria. So far there is only on species of this genus known (Quatrionicoccus australiensis).