[Class] Polycystinea Ehrenberg, 1838 - polycystines see Superclass Polycystinia Ehrenberg, 1838 Order Nassellaria Ehrenberg, 1875 see Class Nassellaria Ehrenberg, 1847 Family Plagiacanthidae Hertwig, 1879 Genus Plectagonidium Cachon & Cachon, 1969 Plectagonidium deflandrei Cachon & Cachon, 1969