In 2003, a new gall-inducing wasp of the genus Ophelimus was detected in the Valparaíso Region (Chile), affecting tree plantations of Eucalyptus globulus Labill and Eucalyptus camaldulensis Dehnh. Since then Ophelimus has been frequently detected in different plantations in Chile, covering a widespread area. A preliminary collaborative study suggests that the micro-wasp detected should be classified as a new Ophelimus species. In this paper, using an integrative approach (including genetic, morphological, and behavioral data), we addressed the delimitation and description of this new species. This study involved the use of brood adult specimens, raised at the laboratory of MIPlagas Ltda., from infested twigs of E. globulus collected in several localities between of Valparaíso and Los Lagos Regions (Chile). Morphological structures were described according to current Eulophidae taxonomic keys, as well as additional traits, such as gall morphology and behavior. Genetic characterization was implemented using a phylogenetic approach, based on a 648 bp specific fragment of the mitochondrial Cytochrome Oxidase I gene (COI 5 region) obtained from collected specimens and available databases (Genbank, NCBI, and BOLDSystem). Specifically, distinctive patterns of variation were detected in traits like gall and antennae morphology, growth habit trends, and a notorious polyphenism in the setae from the sub marginal vein. Overall evidence suggests that this new entity should be considered a new species in Ophelimus, which is henceforth named Ophelimus migdanorum Molina-Mercader.

Wasps that belong to the genus Ophelimus develop galls on Eucalyptus spp., and E. globulus is considered among the most susceptible species. In 2003, a new species of Ophelimus was detected in Chile. This species forms galls on E. globulus and E. camaldulensis, and it was recently considered as Ophelimus migdanorum nov sp. The present study was carried out 16 yr after its detection and it was aimed to determine the presence of Ophelimus in plantations of E. globulus located in Maule, Biobío and La Araucanía Regions, which represent 76% of the area covered with this species in the country. Between August and September 2017, a total of 165 sampling forest farms were established in stands of E. globulus, located in these regions of the country. In each farm, twigs were collected that represented formation of galls and maintained in laboratory conditions until the emergence of adults. These were identified according to their external morphological characteristics. The presence of O. migdanorum and Closterocerus chamaeleon was determined. Both species emerged together in all the regions considered in the study, 92.1% and 46.7% of the evaluated forest farms, respectively. Then Ophelimus migdanorum is widely distributed in Maule, Biobío and La Araucanía Regions, in Chile.