A new genus and species, Paleodoris lattini gen. n., sp. n. of palm bugs (Hemiptera: Thaumastocoridae, Xylastodorinae) in Dominican amber represents the first description of a fossil thaumastocorid. The new taxon is near Xylastodoris, an extant genus native to Cuba, but differs from it in the size and shape of the clypeus, mandibular plates and pronotum. The fossil shows a similar morphology (flattened body and legs, porrect head, smooth body surface) to X. luteolus, which inhabits the confined spaces between the closed leaves of the Royal Palm (Roystonea regia). By comparative functional morphology, we presume that the fossil species lived in a similar habitat, possibly between the pinnae of palms that grew in the Dominican Republic some 20-40 million years ago.