Surveys for egg-parasitoid wasps were conducted in Rafsanjan, Iran, on two species of Pentatomidae (Hemiptera) found in pistachio orchards, Acrosternum arabicum Wagner and Brachynema signatum Jakovlev. Five species of Scelionidae (Platygastroidea) were recovered, including one that is here described as new: Psix saccharicola (Mani), Trissolcus colemani (Crawford), T. darreh Talamas sp. nov., T. perepelovi (Kozlov), and T. semistriatus (Nees). In addition to describing a new species, we report new host associations, provide COI barcodes for four of these species, and discuss host-related intraspecific variation in T. darreh and T. perepelovi.