Five new Amphibolips Reinhard, 1865 (Hymenoptera, Cynipidae) species from western and southern Mexico: expanding the diversity of oak gall wasps and revealing the largest oak apple gall in the Americas

Five new species of oak gall wasps of the genus Amphibolips Reinhard, 1865 (Cynipidae, Cynipini) are described from Mexico. Amphibolips megalokokka Nieves-Aldrey & Castillejos-Lemus sp. nov. and Amphibolips oyamai Castillejos-Lemus & Nieves-Aldrey sp. nov. from the Trans-Mexican Volcanic Belt (TMVB) exhibit unique morphological characteristics within the genus, particularly in gall morphology. Three additional species, Amphibolips zapoteco Nieves-Aldrey & Castillejos-Lemus sp. nov., Amphibolips idiopteryx Nieves-Aldrey & Castillejos-Lemus sp. nov. and Amphibolips darioi Castillejos-Lemus & Nieves-Aldrey sp. nov., are described from Oaxaca State.

These Oaxacan species show remarkable morphological similarity while providing important insights into the relationships among species within the Oaxacan clade. Based on a prior phylogenetic study using ultraconserved elements, we describe these five new species with supporting evidence from both morphology and molecular data. We also examined the great morphological variation in Trans-Mexican Volcanic Belt species, including both generations of one species, and discusses species richness, phylogenetic relationships, and taxonomic challenges within the genus.