Rhodospirillum  

What you should know:

Rhodospirillum is a member of the so-called purple non-sulfur bacteria. It is an anaerobic, anoxygenic photoheterotroph that uses bacteriochlorophyll and organic electron donors in photosynthesis. 

Classification: 

 Domain Bacteria

    Phylum Proteobacteria 

        Class α - Proteobacteria 

Bergey's Manual Volume 2: The Proteobacteria