New rRNA Gene-Based Phylogenies of the Alphaproteobacteria Provide Perspective on Major Groups, Mitochondrial Ancestry and Phylogenetic Instability
Figure 5
Proposed subclasses of the Alphaproteobacteria.
The three proposed subdivisions are the Magnetococcidae, the Rickettsidae and the Caulobacteridae. Furthermore, the Holosporaceae should be removed from the Rickettsiales, however the identities of the family-level subdivisions of the Holosporales, such as the Holosporaceae (marked with an asterisk), are beyond the scope of this work. Under this scheme the Rickettsiales are comprised solely of the Rickettsiaceae, Anaplasmataceae and Midichloriaceae. The protomitochondrion (†) is an extinct organism that gave rise to the mitochondrial organelles of eukaryotes.