Morphology of sting apparatus of Chrysidoidea (Hymenoptera, Aculeata)

Hymenoptera (sawflies, wasps, ants, and bees) are one of four mega-diverse insect orders, comprising more than 153,000 described and possibly up to one million undescribed extant species [1, 2]. As parasitoids, predators, and pollinators, Hymenoptera play a fundamental role in virtually all terrestrial ecosystems and are of substantial economic importance [1, 3]. To understand the diversification and key evolutionary transitions of Hymenoptera, most notably from phytophagy to parasitoidism and predation (and vice versa) and from solitary to eusocial life, we inferred the phylogeny and divergence times of all major lineages of Hymenoptera by analyzing 3,256 protein-coding genes in 173 insect species. Our analyses suggest that extant Hymenoptera started to diversify around 281 million years ago (mya). The primarily ectophytophagous sawflies are found to be monophyletic. The species-rich lineages of parasitoid wasps constitute a monophyletic group as well. The little-known, species-poor Trigonaloidea are identified as the sister group of the stinging wasps (Aculeata). Finally, we located the evolutionary root of bees within the apoid wasp family "Crabronidae." Our results reveal that the extant sawfly diversity is largely the result of a previously unrecognized major radiation of phytophagous Hymenoptera that did not lead to wood-dwelling and parasitoidism. They also confirm that all primarily parasitoid wasps are descendants of a single endophytic parasitoid ancestor that lived around 247 mya. Our findings provide the basis for a natural classification of Hymenoptera and allow for future comparative analyses of Hymenoptera, including their genomes, morphology, venoms, and parasitoid and eusocial life styles.

The stinging wasps (Hymenoptera: Aculeata) are an extremely diverse lineage of hymenopteran insects, encompassing over 70,000 described species and a diversity of life history traits, including ectoparasitism, cleptoparasitism, predation, pollen feeding (bees [Anthophila] and Masarinae), and eusociality (social vespid wasps, ants, and some bees) [1]. The most well-studied lineages of Aculeata are the ants, which are ecologically dominant in most terrestrial ecosystems [2], and the bees, the most important lineage of angiosperm-pollinating insects [3]. Establishing the phylogenetic affinities of ants and bees helps us understand and reconstruct patterns of social evolution as well as fully appreciate the biological implications of the switch from carnivory to pollen feeding (pollenivory). Despite recent advancements in aculeate phylogeny [4-11], considerable uncertainty remains regarding higher-level relationships within Aculeata, including the phylogenetic affinities of ants and bees [5-7]. We used ultraconserved element (UCE) phylogenomics [7, 12] to resolve relationships among stinging-wasp families, gathering sequence data from >800 UCE loci and 187 samples, including 30 out of 31 aculeate families. We analyzed the 187-taxon dataset using multiple analytical approaches, and we evaluated several alternative taxon sets. We also tested alternative hypotheses for the phylogenetic positions of ants and bees. Our results present a highly supported phylogeny of the stinging wasps. Most importantly, we find unequivocal evidence that ants are the sister group to bees+apoid wasps (Apoidea) and that bees are nested within a paraphyletic Crabronidae. We also demonstrate that taxon choice can fundamentally impact tree topology and clade support in phylogenomic inference.

Hymenoptera is an extraordinarily diverse lineage, both in terms of species numbers and morphotypes, that includes sawflies, bees, wasps, and ants. These organisms serve critical roles as herbivores, predators, parasitoids, and pollinators, with several species functioning as models for agricultural, behavioral, and genomic research. The collective anatomical knowledge of these insects, however, has been described or referred to by labels derived from numerous, partially overlapping lexicons. The resulting corpus of information—millions of statements about hymenopteran phenotypes—remains inaccessible due to language discrepancies. The Hymenoptera Anatomy Ontology (HAO) was developed to surmount this challenge and to aid future communication related to hymenopteran anatomy. The HAO was built using newly developed interfaces within mx, a Web-based, open source software package, that enables collaborators to simultaneously contribute to an ontology. Over twenty people contributed to the development of this ontology by adding terms, genus differentia, references, images, relationships, and annotations. The database interface returns an Open Biomedical Ontology (OBO) formatted version of the ontology and includes mechanisms for extracting candidate data and for publishing a searchable ontology to the Web. The application tools are subject-agnostic and may be used by others initiating and developing ontologies. The present core HAO data constitute 2,111 concepts, 6,977 terms (labels for concepts), 3,152 relations, 4,361 sensus (links between terms, concepts, and references) and over 6,000 text and graphical annotations. The HAO is rooted with the Common Anatomy Reference Ontology (CARO), in order to facilitate interoperability with and future alignment to other anatomy ontologies, and is available through the OBO Foundry ontology repository and BioPortal. The HAO provides a foundation through which connections between genomic, evolutionary developmental biology, phylogenetic, taxonomic, and morphological research can be actualized. Inherent mechanisms for feedback and content delivery demonstrate the effectiveness of remote, collaborative ontology development and facilitate future refinement of the HAO.