Methanomicrobiales
In the taxonomy of microorganisms, the Methanomicrobiales are an order of the Methanomicrobia.  Methanomicrobiales are strictly carbon dioxide reducing methanogens, using hydrogen or formate as the reducing agent.
As seen from the phylogenetic tree based on 'The All-Species Living Tree' Project the family Methanomicrobiaceae is highly polyphyletic within the Methanomicrobiales.

Phylogeny
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN) and National Center for Biotechnology Information (NCBI)
and the phylogeny is based on 16S rRNA-based LTP release 106 by 'The All-Species Living Tree' Project.

Notes:
♠ Strains found at the National Center for Biotechnology Information (NCBI) but not listed in the List of Prokaryotic names with Standing in Nomenclature (LPSN)