The family Miridae is the most diverse and one of the most economically important groups in Heteroptera. However, identification of mirid species on the basis of morphology is difficult and time-consuming. In the present study, we evaluated the effectiveness of COI barcoding for 123 species of plant bugs in seven subfamilies. With the exception of three Apolygus species—A. lucorum, A. spinolae, and A. watajii (subfamily Mirinae)—each of the investigated species possessed a unique COI sequence. The average minimum interspecific genetic distance of congeners was approximately 37 times higher than the average maximum intraspecific genetic distance, indicating a significant barcoding gap. Despite having distinct morphological characters, A. lucorum, A. spinolae, and A. watajii mixed and clustered together, suggesting taxonomic revision. Our findings indicate that COI barcoding represents a valuable identification tool for Miridae and can be economically viable in a variety of scientific research fields.

Previous phylogenetic studies of the tribe Synergini were focused on Palaearctic material, in which the genus Synergus was recovered as monophyletic, despite evidence of non-monophyly when global sampling is considered. A global molecular phylogeny of Synergini, including sequenced material from Nearctic and Neotropical realms, is presented herein for the first time. We assembled DNA data for 120 specimens: 104 representing all genera belonging to Synergini, except for the rare monospecific genus Agastoroxenia (ingroup), and 16 belonging to five other tribes of Cynipidae (outgroup). We obtained sequences for four genes: cytochrome c oxidase subunit I (COI), cytochrome b (Cytb), 28S region D2 (28S D2) and 28S region D3 (28S D3). The evaluated analyses support the non-monophyly of both Saphonecrus and Synergus (with Nearctic and Neotropical Synergus resolved into three clades separated from the Palaearctic species), as well as the monophyly of the rest of the genera in Synergini. Furthermore, the results suggest that neither Saphonecrus s.s. nor Synergus s.s. are present in the New World. The future challenges to separate the clades of Saphonecrus and Synergus into new taxa are discussed. Lastly, Rhoophilus was shown to belong to a new tribe, Rhoophilini trib. nov., on the basis of molecular, morphological and biological data.

Recent years have seen rapid advances in the study of Fagaceae-associated gall wasps (Hymenoptera: Cynipidae) of the Eastern Palaearctic and the Oriental (EPO) regions, for both the gall inducing Cynipini (commonly termed oak gall wasps though many species gall non-oak Fagaceae) and the predominantly inquiline tribes Synergini and Ceroptresini. This process has propagated some taxonomic errors and involves many taxa whose taxonomic status is uncertain. To provide a stable foundation for further advance, here we review the taxonomic status of the 212 species (133 oak gall wasps and 79 oak cynipid inquilines) that have been described or recorded in these regions. Of this total, we treat 171 as valid species names (103 oak gall wasps and 68 oak cynipid inquilines) in 20 genera; 22 as synonym names, 13 as incertae sedis, three as nomen dubium, and three as species inquirenda. Callirhytis kunugicola Shinji, 1944 is proposed as syn. nov. of C. kunugicola Shinji, 1943, as Shinji described the same species twice. For all valid species names, we provide taxonomic references, synonyms, and geographical distributions. We summarize what is known of host plant associations and gall locations for gall inducers, and host associations for inquilines. We discuss geographic patterns in the known richness of currently valid species for both groups of organisms, and place this in the context of the biogeography of available Fagaceae host plants. We provide a brief historical review of the study of oak gall wasps and their inquilines in the EPO regions.