Related how?

Biota (Life)
Prokaryotes (Prokaryota)
Archaea (Archaebacteria)
Euryarchaeota
Methanobacteria

Methanobacteriales (3316454)

Children (2 direct children, 74 direct and indirect children):

Methanobacteriaceae (tree size 68)

Methanothermaceae (tree size 4)