The genus Synergus Hartig (Hymenoptera: Cynipidae: Synergini) in the New World: a complete taxonomic revision with a key to species Author Lobato-Vila, Irene Author Pujade-Villar, Juli 0000-0001-7798-2717 jpujade@ub.edu text Zootaxa 2021 2021-01-12 4906 1 1 121 journal article 8839 10.11646/zootaxa.4906.1.1 308129a3-a99f-4012-bb41-d3220692c398 1175-5326 4434000 09383AAD-8E30-4E50-A533-C6DA4D00E33C Synergus magnus Gillette, 1891 nomen dubium Synergus magnus Gillette, 1891 . Bull. Ill. State Lab. Nat. Hist. 3: 202. Type material: presumably lost. Distribution. USA : Michigan ( Gillette 1891 ). Biology. Reared from galls of Amphibolips cookii Gillette, 1888 ( Gillette 1891 ) , which produces bud galls on Q. rubra ( Burks 1979 ) . Remarks. Synergus magnus was described from a single female ( Gillette 1891: 202 ), whose current location is unknown. According to the original description, the female has 15-segmented antenna, a trait that it shares only with a few species from the New World. However, the description of S. magnus is insufficient to decide whether it is a valid species or a synonym of one of these species with females with 15-segmented antenna. Based on the traits provided by Gillette (1891) , S. magnus might well be a synonym of S. dorsalis , but we first need to find and examine the holotype of S. magnus to confirm this assumption. Hence, we consider S. magnus as nomen dubium until its type material is found and studied in detail.