Nemertodermatida is a class of Xenacoelomorpha, comprising 18 species of millimetre-sized , mostly interstitial worms.
The order Nemertodermatida contains two families with 6 genera. The high level of cryptic diversity in this meiofauna group however implies that the number of nemertodermatid taxa may be underestimated.
The family Ascopariidae <small>Sterrer, 1998</small> contains two genera.
There are 3 species in the family Ascopariidae.
The family Nemertodermatidae <small>Steinböck, 1930</small> contains four genera.
There are 15 species in the family Nemertodermatidae.