A new genus of the family Leptohyphidae is described and illustrated. Three species are treated: Lumahyphes guacra sp. n., described from male and female imagines and nymphs from Argentina and Bolivia; Lumahyphes yagua sp. n., described from male and female adults and a nymph from Colombia and Peru; in addition, Lumahyphes sp. is discussed and illustrated from two male subimagines from Mexico.