Functional Anatomy of Split Compound Eyes of the Whirligig Beetles Dineutus mellyi (Coleoptera: Gyrinidae).

The functional anatomy of the split compound eyes of whirligig beetles Dineutus mellyi (Coleoptera: Gyrinidae) was examined by advanced microscopy and microcomputed tomography. We report the first 3D visualization and analysis of the split compound eyes. On average, the dorsal and ventral eyes contain 1913 ± 44.5 facets and 3099 ± 86.2 facets, respectively. The larger area of ventral eyes ensures a higher field of vision underwater. The ommatidium of the split compound eyes is made up of laminated cornea lenses that offer protection against mechanical injuries, bullet-shaped crystalline cones that guide light to the photoreceptive regions, and screening pigments that ensure directional light passage. The photoreceptive elements, made up of eight retinular cells, exhibit a tri-tiered rhabdom structure, including the upper distal rhabdom, a clear zone that ensures maximum light passage, and an enlarged lower distal rhabdom that ensures optimal photon capture.

The Morphological Transformation of the Thorax during the Eclosion of Drosophila melanogaster (Diptera: Drosophilidae).

The model organism Drosophila melanogaster, as a species of Holometabola, undergoes a series of transformations during metamorphosis. To deeply understand its development, it is crucial to study its anatomy during the key developmental stages. We describe the anatomical systems of the thorax, including the endoskeleton, musculature, nervous ganglion, and digestive system, from the late pupal stage to the adult stage, based on micro-CT and 3D visualizations. The development of the endoskeleton causes original and insertional changes in muscles. Several muscles change their shape during development in a non-uniform manner with respect to both absolute and relative size; some become longer and broader, while others shorten and become narrower. Muscular shape may vary during development. The number of muscular bundles also increases or decreases. Growing muscles are probably anchored by the tissues in the stroma. Some muscles and tendons are absent in the adult stage, possibly due to the hardened sclerites. Nearly all flight muscles are present by the third day of the pupal stage, which may be due to the presence of more myofibers with enough mitochondria to support flight power. There are sexual differences in the same developmental period. In contrast to the endodermal digestive system, the functions of most thoracic muscles change in the development from the larva to the adult in order to support more complex locomotion under the control of a more structured ventral nerve cord based on the serial homology proposed herein.

The fecal shield is a double-edged sword for larvae of a leaf beetle.

Larvae of some leaf beetles carry masses of feces covering parts or all of the body, which is called a "fecal shield". In general, the shield is thought to be a defense structure against natural enemies. However, some studies have suggested that defense effectiveness varies depending on the natural enemy. In this study, we used a fecal retention leaf beetle Ophrida xanthospilota (Coleoptera: Chrysomelidae), and 2 local generalist predators (an ant, Camponotus japonicus (Hymenoptera: Formicidae) and a stinkbug, Arma custos [Hemiptera: Pentatomidae]) as a system to test the hypothesis that the fecal shield of O. xanthospilota plays different roles in predation behavior of different predators and can provide multiple chemical communication signals in predator-prey interactions. Prey bioassays showed that the fecal shield of O. xanthospilota larvae repelled the ant C. japonicus while attracting the stinkbug A. custos. The results also strongly demonstrated that hexane extracts of the fecal shield significantly repelled C. japonicus, while dichloromethane (DCM) extracts did not inhibit ant predation. Interestingly, DCM extracts attracted A. custos, but hexane extracts did not. Therefore, we suggest that the fecal shield is a double-edged sword for the larvae of O. xanthospilota. Our results also indicated that the risk-benefit tradeoff of an insect should be estimated at a community level involving multiple enemies (predators and parasites) and herbivores, rather than in a single prey-predator pair.

Climate shapes the spatiotemporal variation in color morph diversity and composition across the distribution range of Chrysomela lapponica leaf beetle.

Color polymorphism offers rich opportunities for studying the eco-evolutionary mechanisms that drive the adaptations of local populations to heterogeneous and changing environments. We explored the color morph diversity and composition in a Chrysomela lapponica leaf beetle across its entire distribution range to test the hypothesis that environmental and climatic variables shape spatiotemporal variation in the phenotypic structure of a polymorphic species. We obtained information on 13 617 specimens of this beetle from museums, private collections, and websites. These specimens (collected from 1830-2020) originated from 959 localities spanning 33° latitude, 178° longitude, and 4200 m altitude. We classified the beetles into five color morphs and searched for environmental factors that could explain the variation in the level of polymorphism (quantified by the Shannon diversity index) and in the relative frequencies of individual color morphs. The highest level of polymorphism was found at high latitudes and altitudes. The color morphs differed in their climatic requirements; composition of colour morphs was independent of the geographic distance that separated populations but changed with collection year, longitude, mean July temperature and between-year temperature fluctuations. The proportion of melanic beetles, in line with the thermal melanism hypothesis, increased with increasing latitude and altitude and decreased with increasing climate seasonality. Melanic morph frequencies also declined during the past century, but only at high latitudes and altitudes where recent climate warming was especially strong. The observed patterns suggest that color polymorphism is especially advantageous for populations inhabiting unpredictable environments, presumably due to the different climatic requirements of coexisting color morphs.

A new genus of Languriinae from Mexico (Coleoptera, Erotylidae), with comments on the potential mimic phenomenon of some languriines.

A new genus of Languriinae, Tomolanguria Huang, gen. nov. is erected for a single species, Languria aculeata Gorham, 1887 from Mexico. It is similar to the Neotropical genus Languria Latreille, 1802. The differential diagnosis of this new genus is based on the structural features of the elytral apices and slight impressions present on each elytron. Languria aculeata is designated as the type species of the new genus. This species is redescribed and illustrated (all the three specimens examined are shown in the dorsal, ventral, and lateral views). Finally, a mimic relationship between this new genus and genus Paederus Fabricius, 1775 (Staphylinidae) is discussed.

A taxonomic review of the genus Callilanguria Crotch, 1876 (Coleoptera: Erotylidae: Languriinae).

A worldwide review of the genus Callilanguria is presented. Three new species are described: C. weiweii Huang Yang, sp. nov. from Sabah, Malaysia; C. helleri Huang Yang, sp. nov. from Panay, the Philippines; and C. nigripes Huang Yang, sp. nov. from Samar Island, the Philippines. Callilanguria scrupulosa Heller, 1918 is transferred to the genus Doubledaya. The other species are C. eximia Fowler, 1885; C. gorhami Villiers, 1945; C. asymmetrica Heller, 1900; C. ruficeps Achard, 1923; C. milloti Villiers, 1945; C. stenosoma (Harold, 1879); C. flaviventris Fowler, 1886; C. wallacii Crotch, 1876; and C. luzonica Crotch, 1876. In total, twelve species are recognized in the genus Callilanguria, and a key to the described species of the genus is provided.