We describe a new species of softtail, genus Thripophaga, from the southern portion of the delta of the Orinoco River in Venezuela. In plumage the new species is most similar to the Orinoco Softtail (T. cherriei) from the upper Rio Orinoco and to the Striated Softtail (T. macroura) of southeastern Brazil. It differs from either in voice, plumage, and mensural characters, but, like these two species, it has a small and geographically isolated range. The new taxon, as far as is currently known, is restricted to seasonally flooded forest along streams and rivers in the vicinity of the Brazo Imataca, a closed loop branch of the Rio Grande, which is the largest branch of the Rio Orinoco passing through the southern part of the Orinoco delta. We also present notes on the behavior, ecology, and conservation of this species.