Eight new species of cynipid inquilines, Synergus abei Melika & Schwéger, S. belizinellus Schwéger & Melika, S. changtitangi Melika & Schwéger, S. formosanus Schwéger & Melika, S. ishikarii Melika & Schwéger, S. kawakamii Tang & Melika, S. khazani Melika & Schwéger and S. symbioticus Schwéger & Melika, from the Eastern Palaearctic are described. Descriptions, diagnoses, biology, and host associations for the new species and a key to all known Eastern Palaearctic Synergus species are given. All taxa are supported by morphological and molecular data. We discuss the status of all previously described Eastern Palaearctic Synergus species, and provide validation and synonymization of some species.

Cynipid gallwasps comprise 1364 species worldwide, predominantly in temperate regions of the Holarctic. The vast majority of recorded species are from the Nearctic and the Western Palaearctic, both of which are long-standing centers of research on the taxonomy and biology of this group. In contrast, the Eastern Palaearctic and the Oriental Region faunas are much less studied, but potentially extremely rich. Previously recorded species richness of cynipid groups in the Eastern Palaearctic and Oriental regions probably represents a significant underestimate. This is particularly marked for gallwasps associated with oaks (tribe Cynipini), as has been shown by recent works, which describe many new species galling oaks in the subgenera Quercus and Cyclobalanopsis and plants of the other Fagaceae genera (Castanopsis, Lithocarpus and Castanea). In the present paper, we summarise the current knowledge of oak gallwasps in the regions that extend from Pakistan, through Nepal and China to Japan and south to Indonesia, and list a total of 97 species of Cynipini from the area.

Eight new species of cynipid gallwasps, Cycloneuroterus abei Melika & Tang, C. ergei Tang & Melika, C. gilvus Melika & Tang, C. globosus Melika & Tang, C. jianwui Tang & Melika, C. lohsei Melika & Tang, C. tumiclavus Tang & Melika, C. uraianus Tang & Melika, from Taiwan and mainland China are described. Descriptions, diagnoses, biology, and host associations for the new species and a key to all Cycloneuroterus species are given. All taxa are supported by morphological and molecular data. Seven newly described species induce galls on Quercus subgenus Cyclobalanopsis, while one, C. uraianus, induces galls on Castanopsis. This is the first Cycloneuroterus species known to associate with Castanopsis.

Fifteen new species of cynipid inquilines, Saphonecrus chinensis Tang & Schwéger, S. gilvus Melika & Schwéger, S. globosus Schwéger & Tang, S. leleyi Melika & Schwéger, S. lithocarpii Schwéger & Melika, S. longinuxi Schwéger & Melika, S. morii Schwéger & Tang, S. nantoui Tang, Schwéger & Melika, S. nichollsi Schwéger & Melika, S. pachylomai Schwéger, Tang & Melika, S. robustus Schwéger & Melika, S. saliciniai Melika, Tang & Schwéger, S. shanzhukui Melika & Tang, S. symbioticus Melika & Schwéger, and S. taitungi Schwéger, Tang & Melika, from the Eastern Palaearctic are described. Descriptions, diagnoses, biology, and host associations for the new species, and a key to Palaearctic Saphonecrus species are given. All new taxa form distinct units as demonstrated by the molecular phylogenetic analyses of Palaearctic Saphonecrus species. The status of some earlier described Saphonecrus species is discussed also. The Synergini genus Lithonecrus Nieves-Aldrey & Butterill, 2014 is synonymized with Lithosaphonecrus Tang, Melika & Bozsó, 2013. Three Saphonecrus species are transferred to Synergus: Synergus brevis (Weld) comb. nova, Synergus hupingshanensis (Liu, Yang & Zhu) comb. nova, and Synergus yukawai (Wachi, Ide & Abe) comb. nova. Synophrus vietnamensis Abe, Ide, Konishi & Ueno is transferred to Lithosaphonecrus: Lithosaphonecrus vietnamensis Abe, Ide, Konishi & Ueno), comb. nova. The current number of valid Saphonecrus species worldwide is 36.

Our knowledge about gall wasps associated with the diverse East Asian oaks, Castanopsis and Cyclobalanopsis, is limited due to the lack of extensive field studies. All of the new species concepts are supported by morphological and molecular data. We provide descriptions, diagnoses, host associations for the new species and an illustrated identification key to Eastern Palaearctic Dryocosmus species. We represent natural language phenotypes in a semantic format supported by biomedical ontologies to increase the accessibility of morphological data.