A new genus, Escaphiella, is established for a group of 36 oonopid species found from the United States south to Chile and Argentina. The previously known species had been placed in Scaphiella Simon, and Escaphiella is hypothesized to be the sister group of that genus. Members of the two groups share a laterally extended ventral abdominal scutum and a distinctive female genitalic conformation, but differ in cheliceral shape and setation, female palpal tarsal shape, male and female palpal tarsal setation, embolus form, and posterior respiratory structure. At least seven species of Escaphiella are characterized by the highly unusual occurrence of asymmetry between the right and left male pedipalps. In at least eight species, the right and left posterior median spinnerets are fused into a single median projection, or even lost entirely. Nine specific names are transferred from Scaphiella: S. hespera Chamberlin (chosen as the type species), S. litoris Chamberlin, S. juvenilis (Gertsch and Davis), S. iguala Gertsch and Davis, S. schmidti Reimoser, S. gertschi Chickering, S. itys Simon, S. scutata Chickering, and S. argentina Birabén. Two of those names are newly synonymized: E. juvenilis with E. hespera, and E. scutata with E. itys. The female of E. hespera is described for the first time, and 29 new species are described: E. nye from California and Nevada, E. acapulco, E. colima, E. catemaco, E. tonila, E. chiapa, E. nayarit, E. magna, and E. olivacea from Mexico, E. viquezi from Honduras and Nicaragua, E. tayrona, E. betin, and E. gigantea from Colombia, E. bolivar from Venezuela, E. cidades, E. hesperoides, E. maculosa, E. cachimbo, E. aratau, E. bahia, E. pocone, E. blumenau, and E. morro from Brazil, E. exlineae from Peru, E. peckorum from Argentina, E. ramirezi from Argentina and Uruguay, E. ocoa from Chile, and E. cristobal and E. isabela from the Galapagos Islands.