We discuss the taxonomy of oak gallwasps (Hymenoptera: Cynipidae: Cynipini) whose lifecycle involves only Palaearctic oaks (Quercus subgen. Quercus) in the section Cerris. Recent phylogenetic reconstructions support a deep split between such Cerris-associated species in the genera Aphelonyx, Dryocosmus, Plagiotrochus, Neuroterus, Pseudoneuroterus and species and genera associated with oaks in the section Quercus sensu stricto. We reappraise the generic limits of the Cerris-associated genera, proposing new limits for Dryocosmus, Pseudoneuroterus and Neuroterus, establishing a new genus Cerroneuroterus, elevating Latuspina to a genus level, reestablishing the genera Chilaspis and Trichagalma and proposed new species name combinations. We provide a new key to oak gallwasp genera of the Palaearctic and keys to all species of genera associated with Cerris section oaks. We describe five new species, Aphelonyx kordestanica, Trichagalma formosana, Dryocosmus jungalii, Pseudoneuroterus mazandarani, and P. nichollsi.

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.

A new genus of cynipid oak gallwasp, Cycloneuroterus Melika & Tang (Hymenoptera: Cynipidae: Cynipini), containing five new species, C. lilungi, C. longinuxus, C. lirongchiuea, C. fortuitusus and C. formosanus, is described from Taiwan. Diagnostic characters and generic limits of the new genus are discussed in detail and a key to a group of closely related genera which share a suite of diagnostic genus-level characters is given. Descriptions of galls and adults, data on the diagnosis, distribution, host plant associations and biology of the new species, and a key to all five species are given.

A new genus of cynipid oak gallwasp—Cyclocynips Melika, Tang, & Sinclair (Hymenoptera: Cynipidae: Cynipini), with two new species—C. uberis and C. tumorvirgae—reared from galls on oaks of the Quercus subgenus Cyclobalanopsis is described fromTaiwan. Descriptions of asexual generation adults and their diagnostic characters are presented. The likelihood of yet undiscovered sexual generations and the evolution of host-plant associations in these species are discussed.