methanocalculus halotolerans methanocalculus halotolerans methanocalculus halotolerans is a species of archaeon, the type species of its genus. it is an irregular coccoid hydrogenotrophic methanogen. its type strain is sebr 4845t (= ocm 470t). methanocalculus halotolerans scientific classification domain: archaea kingdom: euryarchaeota phylum: euryarchaeota class: methanomicrobia order: methanomicrobiales family: incertae sedis genus: methanocalculus species: m. halotoleransollivier et al. 1998 nomenclature the name "methanocalculus" has latin roots, "methano" for methane and "calculus" for small round structure, "halo" for salt and "tolerans" for tolerant. in all, the name means salt-tolerant organism with a gravelly body that produces methane.