Adrian Richter

The insect stinger is one of the best‐known animal venom‐delivery structures. Although its internal structure is crucial for venom delivery, key components remain poorly understood. The valvilli are a pair of articulated structures within the valve chamber that act as ‘flaps’ and have often been overlooked or described only superficially. Here, using Diacamma nr. indicum as a model system, we combine high‐resolution micro‐computed tomography (micro‐CT), histological sectioning, serial block‐face scanning electron microscopy (SBF‐SEM) and confocal laser scanning microscopy (CLSM) to characterise the fine‐scale morphology and cuticular material composition of ant valvilli. We report structural differentiation within the valvilli, including distinct cuticular zones that likely correspond to different functions. CLSM imaging particularly highlights variation in sclerotisation, resilin distribution and ultrastructure, indicating that the valvilli are not uniformly flexible elements but rather complex, only partially deformable structures. SBF‐SEM of the distal lobe margin corroborates this material differentiation at the ultrastructural level, revealing a laterally continuous sublayer of regularly spaced, circular domains with reduced electron density, consistent with a periodically organised transition in cuticle composition or architecture at the procuticle level. Furthermore, comparative micro‐CT scans of stingers fixed in different actuation states indicate the involvement of a non‐antiphasic pattern of valvilli movement during stinger deployment, challenging the current understanding of valvilli‐assisted pumping based on rhythmic, alternating movements, as inferred from European honeybees. These findings offer new anatomical insight into the architecture of the ant stinger and provide a refined morphological basis for future studies of venom delivery in Hymenoptera. By clarifying how such delivery systems have been fine‐tuned over the evolution of a hyper‐diverse insect group, they may also inform the design of bio‐inspired micro‐scale injection and pumping systems.

With specialized piercing and sucking mouthparts, hard ticks (Ixodidae) are able to penetrate, anchor and suck blood from their vertebrate hosts. In the process, some species vector diseases that threaten human health and livestock. Historically, much work has been done to characterize their mouthpart anatomy primarily through dissections and histology. Advances in imaging techniques have led to more recent work exploring stages of the tick feeding process including salivation, suction, as well as penetration. However, a comprehensive overview of the internal and external anatomy of the mouthparts, not just in females but also in males, is still lacking. These mouthparts relate to a tick's ability to vector parasites. In this study, we focus on a medically and agriculturally important tick, Haemaphysalis longicornis , native to East Asia, which has spread beyond its original range. Using 3D modeling and confocal laser scanning microscopy, we document mouthpart and head anatomy, with particular focus on components related to penetration. Our results show that: (i) tick mouthparts are composed of different materials with the hypostome and chelicerae showing resilin‐dominated regions, whereas the palps are especially strongly sclerotised; and (ii) ticks have musculature that might be capable of generating hydraulic pressure to drive cheliceral protrusion. Together, these findings highlight how a morphological perspective is crucial to understanding tick mouthparts and their function in blood feeding.

The extinct Eocene fly genus Kelneria Matile, 1979 is characterized by extreme modification of male genitalia within the family Keroplatidae. However, their morphology has remained poorly understood, as fossil material cannot be examined using traditional entomological techniques. To overcome this limitation, we applied micro-computed tomography (µCT) and synchrotron radiation micro-computed tomography (SRµCT) to reconstruct the genitalia through segmentation of scan data, enabling reassessment of the spatial organization and homology of their structures. Our analyses indicate that Kelneria was both morphologically distinctive and well represented in Eocene amber assemblages. They also support the synonymization of the Oise amber genus Eokelneria Hebert, Ngô-Muller & Nel, 2025 with Kelneria Matile, 1979, demonstrating that the characters used to establish Eokelneria fall within the range of variation observed in Kelneria . We further demonstrate that the species-level diversity of Kelneria has been underestimated and describe three new species: Kelneria rovnensis Pełczyńska & Perkovsky sp. nov ., K. erroris Pełczyńska, Krzemiński & Soszyńska sp. nov . and K. szymoni Pełczyńska, Krzemiński & Soszyńska sp. nov . Additionally, identification of representatives in Rovno and Oise ambers extends the geographic and temporal range of the genus to the early Eocene (c. 53 Ma). Taken together, these findings show that Kelneria was an abundant, diverse, and widespread genus in the Eocene but has no modern representatives. The reasons for this extinction remain unknown; however, contrasting distribution of Eocene and extant representatives of the tribe Robsonomyiini suggests that this disappearance may reflect a broader faunal turnover in Europe after the Eocene.

We report the first confirmed occurrence in Germany of the Asian needle ant, Brachyponera chinensis (Emery, 1895), from a complete outdoor colony collected in the Rosensteinpark of Stuttgart during a BioBlitz on 2 June 2025. Based on additional records from Rosensteinpark, it appears that this may be an established local population, capable of surviving over winter, in contrast to other, incidental occurrences in the country. Brachyponera chinensis is native to East Asia and is known as both an ecologically disruptive invasive in parts of the southeastern United States and as a species of medical concern due to allergic reactions from their stings. To aid in morphology-based identification, we refine the diagnosis of this species relative to close congeners. Our record, verified by voucher specimens and morphological comparison, represents a potential early-stage introduction of B. chinensis into Central Europe. The species was likely introduced to the Rosensteinpark through horticultural specimen transfer, as the park includes the zoological-botanical garden Wilhelma. The finding raises questions about possible urban establishment and future spread and emphasizes the need for ongoing monitoring of the ant fauna in Germany.

The internal structure of the insect stinger plays a central role in venom delivery, yet critical components in this process remain poorly understood. Of these, the valvilli, a pair of articulated structures within the valve chamber that act as ‘flaps’, have often been overlooked or described only superficially. Here, we use high-resolution micro-computed tomography (micro-CT), histological sectioning, and confocal laser scanning microscopy (CLSM) to characterize the fine morphology and material composition of the cuticle of ant valvilli. We report structural differentiation within the valvilli, including sharply delimited material zones that may correspond to distinct mechanical properties. CLSM imaging highlights variation in sclerotization, resilin distribution, and ultrastructure, indicating that the valvilli are not uniform flap-like elements but rather complex, partially deformable structures. Furthermore, comparative micro-CT scans of stingers fixed in different actuation states indicate the involvement of a non-antiphasic pattern of valvilli movement during stinger deployment, challenging the current understanding of valvilli-assisted pumping based on rhythmic, alternating movements, as inferred from European honeybees. These findings offer new anatomical insight into the architecture of the ant stinger and provide a refined morphological basis for future studies of venom delivery mechanisms in Hymenoptera; to also foster our understanding of the complex functionality of micro-scale injection and pumping systems in insects.

Ant lifestyles centre around the unique combination of eusociality, flightless workers, and often predatory habits. No morphological innovations in ants are known to relate to predation. Here, we explore an understudied ant novelty: the ability to close off their mouth. Ants lock their labrum in front of the maxillolabial complex through part of the maxilla pressing against labral hooks. Grooves on the maxillolabial complex additionally allow tighter labral fit in some groups. Variations in both mechanisms lead to different levels of mouthpart closure, with an evolutionary trend to switch from looser to tighter conditions across ants. We find predation to predict tight closure, but models of character evolution indicate that evolutionary dependence between these traits is not the only possible explanation for this pattern. Although tight interlocking is lost in some ants, we find no clear evidence for trade-offs with other functions, such as sensing with the palps. We discuss the origin of interlocking in ants and suggest that it might relate to a combination of predation, prognathous mouthparts, and multipurpose mandibles. We discuss the role of mouthpart closure in ant evolution but also highlight limitations of our comparative approach and emphasize the need for focused biomechanical investigations and enhanced natural history data to refine future inferences of adaptation.

The classification of ants (Hymenoptera: Formicidae) has progressed in waves since the first 17 species were described by Linnaeus in the 1758 edition of Systema Naturae. Since then, over 18,000 species-rank names have accumulated for the global myrmecofauna, of which ~14,260 living and ~810 fossil species are valid. Here, we provide a synopsis of ant biodiversity and review the history and classification of the family, while highlighting the massive growth of the field in the new millennium. We observe that major transformation has occurred for ant classification due to advances in DNA sequencing technologies, model-based hypothesis testing, and imaging technologies. We therefore provide a revised and illustrated list of diagnostic character states for the higher clades of Formicidae, recognizing that vastly more work is to be done. To facilitate discussion and the systematic accumulation of evolutionary knowledge for the early evolution of the ants, we suggest an informal nomenclatural system for the higher clades of ants, based on names currently in use and a set of names that have been democratically selected by the authors. To guide future work on ant systematics, we summarize currently available databases and present perspectives on regions in need of biodiversity exploration, challenges facing the field, and the future of ant taxonomy.

Basiceros dirt ants are morphologically distinct and widely distributed members of Neotropical communities. These ants possess features that aid in leaf litter camouflage and are larger than other closely related lineages with similar cryptic adaptations. Here, we report the first fossil of this genus group, Basiceros enana sp. nov., from Miocene-aged Dominican amber, which reveals a pattern of body size evolution and disjunct biogeography. The fossil evidences the local extinction of Basiceros in the Caribbean, even as living Basiceros are known from Honduras to Southern Brazil. Using combined morphological and molecular datasets of all closely related lineages, we recover the evolutionary trajectory for body size within the group, demonstrating that body size was initially small in these ants and followed by a rapid expansion of body size in the common ancestor of all living species. Results reflect the capacity for early morphological evolution to influence perceived patterns of body size increase through a mosaic of ancestral legacy and continuous enlargement.

The study of insect morphology has recently benefited greatly from the emergence of new digital imaging and analysis technologies such as X-ray Micro-computed tomography (μ-CT), digital 3D reconstruction, and animation. Through interactive gaming and virtual reality, the external morphology of insects can be studied by a broad audience of both entomologists ...

As the only direct records of the history of evolution, it is critical to determine the geological source of biota-bearing fossils. Through the application of synchrotron-radiation micro-computed tomography (SR-µ-CT), Fourier-transformed infrared-spectroscopy (FT-IR), visual evaluation of ultraviolet fluorescence (UV-VS), radiocarbon dating (¹⁴C quantification), and historical sleuthing, we were able to identify and sort 161 (83 Baltic amber, 71 Copal and 7 Kauri gum pieces) individually numbered and largely mislabeled pieces of East African Defaunation resin (~145 years old) and copal (~390 years old), as well as Baltic amber (~35 million years old) from the Phyletisches Museum collection. Based on this collection, we define two new species: ‡Amphientomum knorrei Weingardt, Bock & Boudinot, sp. nov. (Psocodea: Amphientomidae, copal) and †Baltistena nigrispinata Batelka, Tröger & Bock, sp. nov. (Coleoptera: Mordellidae, Baltic amber). For selected taxa, we provide systematic reviews of the fossil record, including: Amphientomidae, for which we provide a key to all species of Amphientomum, extant and extinct, and recognize the junior synonymy of Am. ectostriolatum Li, 2002 (an unjustified emendation) under Am. ectostriolate Li, 1999 (syn. nov.); the fossil ant genus †Yantaromyrmex and the clades Dorylinae, Plagiolepidini, Camponotus, Crematogaster, and Pheidole (Formicidae); the Nevrorthidae (Neuroptera); and Doliopygus (Coleoptera: Curculionidae: Platypodinae). We synonymize Palaeoseopsis Enderlein, 1925 with Amphientomum Pictet, 1854, syn. nov. and transfer one species from Amphientomum, forming Lithoseopsis indentatum (Turner, 1975), comb. nov. To prevent the uncritical usage of unidentifiable fossils attributed to Camponotus for macroevolutionary analysis, we transfer 29 species to the form genus †Camponotites Steinbach, 1967, which we consider to be most useful as incertae sedis in the Formicinae. We treat †Ctt. ullrichi (Bachmayer, 1960), comb. nov. as unidentifiable hence invalid stat. nov. We also transfer †Ca. mengei Mayr, 1868 and its junior synonym †Ca. igneus Mayr, 1868 to a new genus, †Eocamponotus Boudinot, gen. nov., which is incertae sedis in the Camponotini. Concluding our revision of Camponotus fossils, we transfer †Ca. palaeopterus (Zhang, 1989) to Liometopum (Dolichoderinae), resulting in †L. palaeopterumcomb. nov. and the junior synonymy of †Shanwangella Zhang, 1989, syn. nov. under Liometopum Mayr, 1861. Because the type specimens of the genera †Palaeosminthurus Pierce & Gibron, 1962, stat. rev. and †Pseudocamponotus Carpenter, 1930 are unidentifiable due to poor preservation, we consider these taxa unidentifiable hence invalid stat. nov. To avoid unsupported use of the available fossils names attributed to Crematogaster for divergence dating calibration points, we transfer three species to a new collective taxon that is incertae sedis in Myrmicinae, †Incertogaster Boudinot, gen. nov., forming †In. aurora (LaPolla & Greenwalt, 2015), †In. praecursor (Emery, 1891), comb. nov., and †In. primitiva (Radchenko & Dlussky, 2019), comb. nov. Finally, we transfer †Ph. cordata (Holl, 1829) back to Pheidole, and designate a neotype from our copal collection based on all available evidence. All new species plus the neotype of ‡Ph. cordata are depicted with 3D cybertypes from our µ-CT scan data. We introduce the convention of a double dagger symbol (‡) to indicate fossils in copal or Defaunation resin, as these may yet be extant. To further contextualize our results, we provide a discussion of amber history and classification, as well as the Kleinkuhren locality, to which multiple specimens were attributed. We conclude with conspecti on key biological problems and increasing potential of µ-CT for phylogenetic paleontology.