A comprehensive data set of hymenopteran mesosomal anatomy is presented and analysed. Eighty-nine taxa, including three outgroups, were scored for 273 characters. Analyses were carried out under different weighting conditions (equal and implied weights). Topologies retrieved for the non-apocritan Hymenoptera were highly congruent with previously published results. Apocrita were always retrieved as monophyletic, as were most superfamilies. Relationships amongst apocritan superfamilies were mostly weakly corroborated. Stephanoidea were almost always the sister group to the remaining Apocrita. Evaniomorpha were usually retrieved, Ceraphronoidea being the sister group to Megalyroidea, and Evanioidea to Trigonaloidea. Aculeata did not always come out as monophyletic, and of the aculeate superfamilies, only Apoidea was retrieved. Ichneumonoidea were always monophyletic and often the sister group of Aculeata. Maamingidae and Mymarommatoidea were usually sister groups; together, they often form the sister group of Chalcidoidea. A large clade comprising Cynipoidea, Platygastroidea, and Proctotrupoidea was usually retrieved, the two former superfamilies being nested within Proctotrupoidea. Cynipoidea were usually closely related to some of the Diapriidae. Platygastroidea were usually the sister group of a clade comprising Heloridae, Pelecinidae, Proctotrupidae, and Vanhorniidae. The mesosomal region proved to be a very substantial source of phylogenetically relevant information. The results of the present analyses indicate that a reclassification, especially of Proctotrupoidea, is required, but this should be carried out after thorough analyses of more comprehensive combined data sets.

Abstract. Published research on the diversity and evolutionary history of Arthropoda sets a high standard for data collection and the integration of novel methods. New phylogenetic estimation algorithms, divergence time approaches, collaborative tools and publishing standards, to name a few, were brought to the broader scientific audience in the context of arthropod systematics. The treatment of morphology in these studies, however, has largely escaped innovation. Lodes rich in characters too often go unexplored, phenotype concepts are published with inadequate documentation and the way observations are textualised leaves them inaccessible to a majority of biologists. We discuss these issues, using data from recent arthropod systematics publications, and offer several that stand to restore the broad utility of morphological data. Specifically, we focus on: (1) the potential of internal soft-part characters and how to integrate their observation into arthropod systematics projects through dissection and serial sectioning; (2) the importance of capturing observations in images, especially using relatively new approaches, like laser scanning confocal microscopy and three-dimensional reconstruction; and (3) the untapped potential of established knowledge representation methods, which may help make the descriptive components of arthropod systematics research more accessible to other domains.

In the current revisionary work, the Temnothorax nylanderi species-group of myrmicine ants is characterized. Eighteen species belonging to this group in the Ponto-Mediterranean region are described or redefined based on an integrative approach that combines exploratory analyses of morphometric data and of a 658bp fragment of the mitochondrial gene for the cytochrome c oxidase subunit I (CO I). The species group is subdivided into five species complexes: T. angustifrons complex, T. lichtensteini complex, T. nylanderi complex, T. parvulus complex, T. sordidulus complex, and two species, T. angulinodis sp. n. and T. flavicornis (Emery, 1870) form their own lineages. We describe seven new species (T. angulinodis sp. n., T. angustifrons sp. n., T. ariadnae sp. n., T. helenae sp. n., T. lucidus sp. n., T. similis sp. n., T. subtilis sp. n.), raise T. tergestinus (FINZI, 1928) stat.n. to species level, and propose a new junior synonymy for T. saxonicus (SEIFERT, 1995) syn.n. (junior synonym of T. tergestinus). We describe the worker caste and provide high quality images and distributional maps for all eighteen species. Furthermore, we provide a decision tree as an alternative identification key that visually gives an overview of this species-group. We make the first application to Formicidae of the Semantic Phenotype approach that has been used in previous taxonomic revisions.

The parasitoid wasp family Ichneumonidae is arguably one of the groups for which current knowledge lags most strongly behind their enormous diversity. In a five-day meeting in Basel (Switzerland) in June 2019, 22 researchers from 14 countries met to discuss the most important issues in ichneumonid research, including increasing the speed of species discovery, resolving higher-level relationships, and studying the radiation of these parasitoids onto various host groups through time. All agreed that it is time to advertise ichneumonid research more broadly in the scientific community and thereby attract young talents to this group for which specialists are sorely lacking. In order to popularize the group, we here suggest a new name for the family, “Darwin wasps”, to reflect the pivotal role they played in convincing Charles Darwin that not all of creation could have been created by a benevolent god. We hope that the name catches on, and that Darwin wasps start buzzing more loudly across all disciplines of biology.

A spectacular hypothesis was published recently, which suggested that the “helmet” (a dorsal thoracic sclerite that obscures most of the body) of treehoppers (Insecta: Hemiptera: Membracidae) is connected to the 1st thoracic segment (T1; prothorax) via a jointed articulation and therefore was a true appendage. Furthermore, the “helmet” was interpreted to share multiple characteristics with wings, which in extant pterygote insects are present only on the 2nd (T2) and 3rd (T3) thoracic segments. In this context, the “helmet” could be considered an evolutionary novelty. Although multiple lines of morphological evidence putatively supported the “helmet”-wing homology, the relationship of the “helmet” to other thoracic sclerites and muscles remained unclear. Our observations of exemplar thoraces of 10 hemipteran families reveal multiple misinterpretations relevant to the “helmet”-wing homology hypothesis as originally conceived: 1) the “helmet” actually represents T1 (excluding the fore legs); 2) the “T1 tergum” is actually the anterior dorsal area of T2; 3) the putative articulation between the “helmet” and T1 is actually the articulation between T1 and T2. We conclude that there is no dorsal, articulated appendage on the membracid T1. Although the posterior, flattened, cuticular evagination (PFE) of the membracid T1 does share structural and genetic attributes with wings, the PFE is actually widely distributed across Hemiptera. Hence, the presence of this structure in Membracidae is not an evolutionary novelty for this clade. We discuss this new interpretation of the membracid T1 and the challenges of interpreting and representing morphological data more broadly. We acknowledge that the lack of data standards for morphology is a contributing factor to misinterpreted results and offer an example for how one can reduce ambiguity in morphology by referencing anatomical concepts in published ontologies.