Mazocraeidea
 Mazocraeidea is an order in the subclass Polyopisthocotylea within class Monogenea.The species of this order have various structures in the clamps of their posterior attachment organ including additional sclerites in the Gastrocotylidae and related families. However these additional sclerites and even the clamps themselves are lacking in certain members of the family Protomicrocotylidae.