Earlier, representatives of the genus were assigned to the family Azotobacteraceae Pribram, 1933, but then were transferred to the family Pseudomonadaceae based on the studies of nucleotide sequences 16S rRNA.
Inicialmente os representantes deste xénero foron asignados á familia Azotobacteraceae PRIBRAM, 1933, pero despois foron transferidos á familia Pseudomonadaceae baseándose en estudos das secuencias de nucleótidos do ARNr de 16S.