Review of the Synergus Hartig Species (Hymenoptera: Cynipidae: Synergini) Associated with Tuberous and Other Tumor-Like Galls on Oaks from the New World with the Description of Three New Species from Mexico

A review of the inquiline oak gall wasp species of the genus Synergus Hartig that are associated with tuberous and other tumor-like galls on oaks (Quercus L.) from the New World is provided for the first time. Redescriptions, remarks, pictures and new location data for the species previously known from the New World are given. Three new species that emerged from tuberous galls collected in Mexico are formally described and illustrated: Synergus grahami Lobato-Vila and Pujade-Villar, sp. nov.; S. shorthousei Lobato-Vila and Pujade-Villar, sp. nov.; and S. tenebrosus Lobato-Vila and Pujade-Villar, sp. nov. A morphological key to identify and separate all the species addressed in this work is given. In addition, Saphonecrus brevicornis (Ashmead, 1896) is returned to Synergus; a new name for Synergus luteusNieves-Aldrey and Medianero, 2011 is given to avoid a primary homonymy with an European species; Synergus multiplicatusFullaway, 1911 becomes a syn. nov. of S. mexicanusGillette, 1896, and S. davisi (Beutenmuller, 1907) a syn. nov. of S. lignicola (Osten-Sacken, 1862).