Phylum Gnathostomulida Ax, 1956 - gnathostomulids Order Bursovaginoidea Sterrer, 1972 Suborder Scleroperalia Sterrer, 1972 Family Onychognathiidae Sterrer, 1972 Genus Valvognathia Kristensen & Nørrevang, 1978 Valvognathia pogonostoma Kristensen & Nørrevang, 1978