methanoculleus submarinus methanoculleus submarinus methanoculleus submarinus is a methanogen. it is non-motile and highly irregular coccoid-shaped (with average diameter of 0.8-2 μm). nankai-1 is its type strain. methanoculleus submarinus scientific classification domain: archaea kingdom: euryarchaeota class: methanomicrobia order: methanomicrobiales family: methanomicrobiaceae genus: methanoculleus species: m. submarinus binomial name methanoculleus submarinusmikucki et al. 2003