methanoplanus endosymbiosus methanoplanus endosymbiosus methanoplanus endosymbiosus is a species of archaeon, an endosymbiont of the marine sapropelic ciliate metopus contortus. it is an irregular, disc-shaped bacterium with a diameter of 1.6–3.4 μms and type strain mc1. its 16s dna was sequenced in 1994, eight years after the initial isolation, and it was found to share considerable similarity with that of methanoplanus limicola. methanoplanus endosymbiosus scientific classification domain: archaea kingdom: euryarchaeota phylum: euryarchaeota class: methanomicrobia order: methanomicrobiales family: methanomicrobiaceae genus: methanoplanus species: m. endosymbiosus binomial name methanoplanus endosymbiosusvan bruggen et al. 1986