This order comprises only one species, Leptosomus discolor, family Leptosomidae. 

References

Mayr G (2008), The Madagascan "Cuckoo-Roller" (Aves: Leptosomidae) is not a roller - notes on the phylogenetic affinities and evolutionary history of a  "living fossil", Acta Ornithol. 43, 226-230. (abstract)