Abstract
A new species of the genus Euderus Haliday, Euderus setsp. n., is described and illustrated from the southeastern United States, where it parasitizes the crypt gall wasp, Bassettia pallida Ashmead, 1896, on live oaks in the genus Quercus (subsection Virentes). This is the 1(st) species of the genus reported from the southeastern United States to parasitize cynipid gall wasps and the 3(rd) species of the genus reported to attack cynipids in North America. Modified sections of the identification keys to subgenera and species of Euderus (Yoshimoto, 1971) are included to integrate the new species.