sentence: Plasmids have been identified in members of the transitional group ( R. felis and R. akari ) , the ancestral group ( R. bellii ) , SFG rickettsiae ( Rickettsia amblyommatis , Rickettsia rhipicephali , Rickettsia monacensis , Rickettsia helvetica , Rickettsia massiliae , and Rickettsia hoogstraalii ) , and Rickettsia buchneri , the rickettsial endosymbiont of Ixodes scapularis ( 11 – 14 ) , but seem to be absent in Rickettsia parkeri , Rickettsia montanensis , R. rickettsii , R. conorii , R. typhi , and R. prowazekii ( 14 ) .