Two new species of Caribbean conocephaline katydids (Agraeciini) are described for the previously monotypic genus Erechthis: one from the island of Eleuthera in the Bahamas, one from Hispaniola. The first-named species Erechthis gundlachi occurs on both Cuba and Hispaniola. A median projection (prong) of the subgenital plate is taken as a major generic diagnostic trait. This structure's morphology suggests a device for removal of rival sperm. The mate attraction song of males of the Eleutheran species is a steadily repeating series of chirps, each composed of 3 – 5 pulse trains. In the audio the frequency spectrum is broadband from 11 to beyond 20 kHz, with a coherent peak near 7 kHz. Inconsistency in some within-male song features may reflect this species' isolation from congenerics. The Eleutheran species bears a striking turquoise-colored face apparently absent in the other two species. We hypothesize that this coloration is a predatoravoidance adaptation. Possible Caribbean dispersal scenarios are discussed for these species.