Family Clionidae Gray, 1840
Clionidae is composed of two subfamilies: the Clioninae and the Thliptodontinae.
The family Clionidae is recognised by the complete absence of gills, the body is usually smooth, the only appendages are those of the buccal mass; some genera have buccal cones. Hook sacs are always present. The wings are found beneath the mouth at both sides of the body with lateral and posterior footlobes in between. In some species these lobes are strongly reduced. Furthermore, the anatomy is the same as in most Gymnosomata.
[2 subfamilies]