Taxonomic review of oak cynipid inquilines (Hymenoptera: Cynipidae), with special attention to the New World fauna and an approach to their global phylogeny

Abstract

The oak cynipid inquilines (Hymenoptera: Cynipidae: Synergini, Ceroptresini) are a group of specialized endophytophagous microhymenopterans that develop inside galls induced mainly by other cynipids on Fagaceae trees, principally oaks (Quercus L.). In this Thesis, a taxonomic review of these organisms, with special attention to the New World fauna (Nearctic and Neotropical regions) and an approach to the global phylogeny of the tribe Synergini, has been carried out. The type material of nearly 80 of the approximately 90 species within the three main genera occurring in the New World (Synergus, Ceroptres, and Saphonecrus) has been located and examined, after which 69 remain as valid: 56 Synergus, 12 Ceroptres, and 1 Saphonecrus. This has made it possible to stabilize the chaotic taxonomy of these organisms in the New World and to provide an adequate scenario for the description of new taxa. In fact, this Thesis adds a significant number of new species and records to the New World fauna: 22 new Synergus and 5 new Ceroptres, plus several new records, from Mexico (whose fauna was poorly characterized despite being among the richest regions of oak diversity worldwide), and 2 new Synergus from Colombia. The genus Synergus has been evaluated through several publications about the Nearctic and Neotropical fauna including redescriptions, illustrations, new biological and distribution data, and identification keys, whereas Ceroptres has been addressed in a worldwide revision of Ceroptresini, in which a new genus, Buffingtonella, has been described. In addition to the New World, this Thesis updates the knowledge about the Eastern Palaearctic and the Oriental fauna through the study of material deposited in different institutions. The validity of previously known species from these regions has been evaluated, and a few new Synergus and Saphonecrus species have been described in various assessments and revisions that include updated keys to species of different genera. Lastly, a molecular phylogeny of Synergini incorporating material of all genera within the tribe (except Agastoroxenia) from all the occurring areas has been carried out. The inclusion of New World sequences brings to light the polyphyly of Synergus, and molecular, morphological, and biological data are considered strong enough to raise the South African endemism Rhoophilus to its own tribe, Rhoophilini.