Distal leg structures of Zoraptera - did the loss of adhesive devices curb the chance of diversification?

TriTrap: A Robotic Gripper Inspired by Insect Tarsal Chains

Gripping, holding, and moving objects are among the main functional purposes of robots. Ever since automation first took hold in society, optimizing these functions has been of high priority, and a multitude of approaches has been taken to enable cheaper, more reliable, and more versatile gripping. Attempts are ongoing to reduce grippers' weight, energy consumption, and production and maintenance costs while simultaneously improving their reliability, the range of eligible objects, working loads, and environmental independence. While the upper bounds of precision and flexibility have been pushed to an impressive level, the corresponding solutions are often dependent on support systems (e.g., sophisticated sensors and complex actuation machinery), advanced control paradigms (e.g., artificial intelligence and machine learning), and typically require more maintenance owed to their complexity, also increasing their cost. These factors make them unsuited for more modest applications, where moderate to semi-high performance is desired, but simplicity is required. In this paper, we attempt to highlight the potential of the tarsal chain principle on the example of a prototype biomimetic gripping device called the TriTrap gripper, inspired by the eponymous tarsal chain of insects. Insects possess a rigid exoskeleton that receives mobility due to several joints and internally attaching muscles. The tarsus (foot) itself does not contain any major intrinsic muscles but is moved by an extrinsically pulled tendon. Just like its biological counterpart, the TriTrap gripping device utilizes strongly underactuated digits that perform their function using morphological encoding and passive conformation, resulting in a gripper that is versatile, robust, and low cost. Its gripping performance was tested on a variety of everyday objects, each of which represented different size, weight, and shape categories. The TriTrap gripper was able to securely hold most of the tested objects in place while they were lifted, rotated, and transported without further optimization. These results show that the insect tarsus selected approach is viable and warrants further development, particularly in the direction of interface optimization. As such, the main goal of the TriTrap gripper, which was to showcase the tarsal chain principle as a viable approach to gripping in general, was achieved.

A new species of Zoraptera, Zorotypuskomatsui sp. nov. from Cameroon and a redescription of Zorotypusvinsoni Paulian, 1951 (Polyneoptera, Zoraptera)

A new species of the order Zoraptera, Zorotypuskomatsui Matsumura, Maruyama, Ntonifor & Beutel, sp. nov., is described from Cameroon. The female and male morphology of another species, Z.vinsoni, is re-described, and its new distribution in Madagascar is recorded. A particular focus is on the male postabdominal morphology. This is apparently a crucial body region in the very small order with an extreme variation of the genital apparatus but otherwise a very uniform morphology. The male of the newly described species shares rudimentary male genitalia and well-developed postabdominal projections with the distantly related Spermozorosimpolitus, apparently a result of parallel evolution. Whether males of Z.komatsui also perform external sperm transfer like S.impolitus remains to be shown. The collecting of the material used for this study suggests that the present knowledge of zorapteran species diversity of the Afrotropical region is very fragmentary.

Morphological and Behavioral Adaptations of Silk-Lovers (Plokiophilidae: Embiophila) for Their Lifestyle in the Silk Domiciles of Webspinners (Embioptera)

The diversity of true bugs gave rise to various lifestyles, including gaining advantage from other organisms. Plokiophilidae are cimicomorphan bugs that live in the silk constructions of other arthropods. One group, Embiophila, exclusively settles in the silk colonies of webspinners (Embioptera). We investigated the lifestyle of Embiophila using microscopy to study the micromorphology and material composition of the leg cuticle, choice assays and retention time measurements based on different characteristics of the embiopteran galleries and tilting experiments with different substrates to quantify the attachment performance of the bugs. Embiophila neither explicitly preferred embiopteran presence, nor required silk for locomotion, but the bugs preferred fibrous substrates during the choice experiments. The hairy attachment pad on the tibia showed the best attachment performance on substrates, with an asperity size of 1 µm. Additionally, very rough substrates enabled strong attachment, likely due to the use of claws. Our findings suggest that Embiophila settle in galleries of webspinners to benefit from the shelter against weather and predators and to feed on mites and other intruders. The combination of behavioral and functional morphological experiments enables insights into the life history of these silk-associated bugs, which would be highly challenging in the field due to the minute size and specialized lifestyle of Embiophila.

An Immature Dermapteran Misidentified as an Adult Zorapteran: The Case of Formosozoros newi Chao & Chen, 2000

Zoraptera shows extreme uniformity in general body morphology, with the exception of Formosozoros (=Zorotypus) newi Chao & Chen, 2000, which stands out in terms of the shape and arrangement of its legs, the cerci, and several other morphological characters. After critical evaluation, we found that this species is not a zorapteran but is instead a nymph (1st instar) of an earwig; i.e., F. newi is a dermapteran. Because of the lack of morphological descriptions of Dermaptera nymphs that would allow species identification, and because the type material of F. newi is lost, a more detailed classification is not possible. We therefore propose that the genus name Formosozoros Chao & Chen, 2000 and the species name Formosozoros newi Chao & Chen, 2000 are nomina dubia.

Cryptic diversity in Zoraptera: Latinozoros barberi (Gurney, 1938) is a complex of at least three species (Zoraptera: Spiralizoridae)

The order Zoraptera contains relatively few species, but current molecular phylogenetic studies suggest an unexpectedly high level of cryptic diversity in the order with many overlooked species based on morphology alone. Latinozoros Kukalova-Peck & Peck, 1993 represents the only genus of monotypic Latinozorinae (Zoraptera: Spiralizoridae) with only one species described, L. barberi (Gurney, 1938), until now. Although this species has been repeatedly reported from a number of locations in South and Central America, it is likely a complex of unrecognized species. Here, we present a molecular phylogenetic reconstruction revealing three genetically distinct lineages in Latinozoros, and we also present detailed morphological comparisons that prove the species status of Latinozoros cacaoensis sp. nov. from French Guiana and L. gimmeli sp. nov. from the Dominican Republic, Trinidad and Panama. The results indicate that the species previously referred to L. barberi is actually a species complex that includes L. barberi, the new species described here, and perhaps other species.