The 36 described species of North and Central American Leptohyphes are discussed and synonymies and other pertinent data are presented for all. Characters allow the North and Central American nymphs to be placed in species-groups; L. dicinctus Allen and Brusca and L. melanobranchus Allen and Brusca in the L. dicinctus-group, and all other described nymphs in the L. apache-group. Accounts are given for the 27 valid species known from the nymphal stage, including an illustrated key, synonymies, description or diagnosis, distribution and new collection records, and maps. L. baumanni Kilgore and Allen is regarded as a synonym of L. mirus Allen, L. consortis Allen of L. sabinas Traver, L. lumas Allen and Brusca of L. hispidus Allen and Brusca, and L. phalarobranchus Kilgore and Allen of L. packeri Allen. L. michaeli sp. nov., L. paraguttatus sp. nov., L. succinus sp. nov. and L. vescus sp. nov. are described from nymphs collected in Texas [USA]; L. piraticus sp. nov., L. vulturnus sp. nov. and L. zelus sp. nov. are described from nymphs collected in Honduras.
