Phylum Tardigrada Doyère, 1840 - tardigrades Order Heterotardigrada Marcus, 1927 see Class Heterotardigrada Marcus, 1927 Suborder Arthrotardigrada Marcus, 1927 see Order Arthrotardigrada Marcus, 1927 Family Stygarctidae Schulz, 1951 Subfamily Stygarctinae Schulz, 1951 see Family Stygarctidae Schulz, 1951