euplotidium euplotidium euplotidium is a genus of ciliates. species form symbiotic relations with bacteria in structures named epixenosomes. euplotidium scientific classification domain: eukaryota (unranked): sar (unranked): alveolata phylum: ciliophora class: spirotrichea subclass: hypotrichia order: euplotida suborder: euplotina family: gastrocirrhidae genus: euplotidiumnoland, 1937 species euplotidium itoi euplotidium prosaltans tuffrau, 1985