The diplomonads are a group of flagellates, most of which are parasitic. They include Giardia lamblia, which causes giardiasis in humans. They are placed among the metamonads, and appear to be particularly close relatives of the retortamonads.Most diplomonads are double cells: they have two nuclei, each with four associated flagella, arranged symmetrically about the body's main axis. Like the retortamonads, they lack both mitochondria and a Golgi apparatus.