We investigated and described the thoracic structures, jumping mechanism, and promesothoracic interlocking mechanism of the click beetle Campsosternus auratus (Drury) (Elateridae: Dendrometrinae). Two experiments were conducted to reveal the critical muscles and sclerites involved in the jumping mechanism. They showed that M2 and M4 are essential clicking-related muscles. The prosternal process, the prosternal rest of the mesoventrite, the mesoventral cavity, the base of the elytra, and the posterodorsal evagination of the pronotum are critical clicking-related sclerites. The destruction of any of these muscles and sclerites resulted in the loss of normal clicking and jumping ability. The mesonotum was identified as a highly specialized saddle-shaped biological spring that can store elastic energy and release it abruptly. During the jumping process of C. auratus, M2 contracts to establish and latch the clicking system, and M4 contracts to generate energy. The specialized thoracic biological springs (e.g., the prosternum and mesonotum) and elastic cuticles store and abruptly release the colossal energy, which explosively raises the beetle body in a few milliseconds. The specialized trigger muscle for the release of the clicking was not found; our study supports the theory that the triggering of the clicking is due to the building-up of tension (i.e., elastic energy) in the system.

In taxonomy, qualitative methods are commonly used to analyze morphological characters, which can lead to dramatic changes in higher taxa. Geometric morphometrics (GM) has proven to be useful for discriminating species in various taxonomy groups. However, the application of geometric morphometrics in supraspecies classification is relatively scarce. In this study, we tested the controversial two subgenera classification of Chaetocnema with geometric morphometrics; a total of 203 Chaetocnema species representing 50% of all known species from around the world were selected for the analysis. We analyzed the shape of the pronotum, elytron, head, aedeagus, and spermatheca. The results showed that the two traditional subgenera distinctly differed from each other; therefore, we propose using two subgenera arrangements to facilitate the understanding and taxonomy of the Chaetocnema species (especially in the Oriental, Palearctic, and Nearctic regions). Additionally, the morphological diversity of the abovementioned structures of Chaetocnema was analyzed, and it was found that the highest morphological diversity was in the spermatheca, which was greater than that in the aedeagus. Our research demonstrated that GM could be useful for detecting morphological delimitation of the supraspecies taxa. It also showed that GM methods are applicable to insects as small as 2 mm in body size.

The Nanling Mountains is one of the sixteen biodiversity hotspots in China. It divides the central and southern regions of the country. This paper documents the diversity of flea beetles in the Nanling Mountains based on a comprehensive insect biodiversity survey from 2020 to 2022. Three new species of the genus Minota Kutschera, 1859 viz. M. cuiae Zhang, Ruan, Liang & Yang sp. nov. (Guangxi), M. maoer Zhang, Ruan, Liang & Yang sp. nov. (Guangxi), and M. bimaculata Zhang, Ruan, Liang & Yang sp. nov. (Jiangxi) from the Nanling Mountains are described and illustrated. A checklist and key to the Chinese Minota species are provided.

Blaiseus Fleutiaux, 1931 is a distinct elaterid genus and readily distinguishable from other Elateridae groups by the strongly flattened fossorial protibia, enlarged femora and tibiae, and the enormously broadened median lobe of genitalia. This study describes and illustrates the Blaiseus dinghuensis Ruan, Qiu & Xie sp. nov. from Guangdong province, China. In addition, an observation of the jumping performance of the new species is made. This represents the third known species of the genus Blaiseus from China and the 12th recognized worldwide.