Nyctotherus ovalis is a single-celled eukaryote that has hydrogen-producing mitochondria and lives in the hindgut of cockroaches. Like all members of the ciliate taxon, it has two types of nuclei, a micronucleus and a macronucleus. N. ovalis generates its macronuclear chromosomes by forming polytene chromosomes that subsequently develop into macronuclear chromosomes by DNA elimination and rearrangement.