Phylum Gnathostomulida Ax, 1956 - gnathostomulids Order Bursovaginoidea Sterrer, 1972 Suborder Scleroperalia Sterrer, 1972 Family Mesognathariidae Sterrer, 1972 Genus Labidognathia Riedl, 1970 Genus Mesognatharia Sterrer, 1966 Genus Tenuignathia Sterrer, 1976