Deutonymphs of two new genera in the family Winterschmidtiidae, subfamily Winterschmidtiinae, are described from the Eastern United States and compared with existing taxa. Bostrichiella delfinadoae gen. nov., sp. nov. is described from Xylobiops basilaris (Say, 1824) from Connecticut, Tennessee, Louisiana and Florida. Xylacarus bauchani gen. nov., sp. nov. is described from Amphicerus bicaudatus (Say, 1824) and A. cornutus (Pallas, 1772), from New Jersey, New York, Michigan and Florida. A few specimens of each species were collected from other bostrichid species. The two new genera are sister-taxa and more closely related to Winterschmidtia than to Parawinterschmidtia. A table of all species included in the Winterschmidtiinae is presented.