Invisible gems: Phylogenomics of Tetrastichinae jewel wasps ( Hymenoptera: Eulophidae ) reveals cryptic taxa and rampant polyphyly

Abstract

Parasitising over 100 families belonging to 10 insect orders, the ubiquitous jewel wasps in the subfamily Tetrastichinae (Chalcidoidea: Eulophidae) are vital to terrestrial ecosystems worldwide as key insect population regulators. Yet this important group, with nearly 2500 described species, is one of the most taxonomically neglected. Here, we present the most detailed phylogenetic hypothesis for the subfamily to date, sampling a third (39/115) of the currently described genera. By analysing three different datasets using both concatenated (IQ‐TREE) and multispecies coalescent approaches (wASTRAL)—3033 Benchmarking Universal Single Copy Orthologs (BUSCOs) for 163 taxa, 1820 Ultraconserved Elements (UCEs) for 219 taxa and 12 mitochondrial genes for 177 taxa—we reveal rampant para‐ and polyphyly at the genus level within Tetrastichinae. Our results also reveal the presence of many undescribed and cryptic species. Overall, we provide a robust phylogenetic hypothesis for the subfamily, highlighting our poor knowledge of the group and calling for a major taxonomic revision of Tetrastichinae at both the generic and species levels. We also present an alternative approach to conducting phylogenomic studies of minute Hymenoptera, using whole‐genome shotgun sequencing instead of relying on a hybrid‐target enrichment approach, demonstrating its efficiency for samples up to 60 years old at the time of extraction. As a product of our bioinformatic workflow, we also provide 164 DNA barcodes and 164 genomes of varying completeness, laying the foundation for future genomic, evolutionary and biodiversity studies of Tetrastichinae.