Ixodides and Uropodina have a number of synapomorphies in common, which are not present in other groups of the Parasitiformes. Anatomicmorphological trends as well as behavioural peculiarities occurring in the carnivorous Uropodina hint to a transition towards parasitism. In fact, feed deficit can lead to parasitism in Uropodina. Based on synapomorphies, Ixodides and Uropodina are combined as Margotrichina n. cohors, Trigynaspina and Sejides as Antennophorina (n. comb.). Those two taxa form a monophyletic group whose sister group are the Gamasina.