[Class] Polycystinea Ehrenberg, 1838 - polycystines see Superclass Polycystinia Ehrenberg, 1838 Order Nassellaria Ehrenberg, 1875 see Class Nassellaria Ehrenberg, 1847 Family Plagiacanthidae Hertwig, 1879 Genus Plectacantha Jørgensen, 1905 Plectacantha oikiskos Jørgensen, 1905