# Sclerites of Bursa Copulatrix Reveal Hidden Generic Diversity in Dimini (Coleoptera, Elateridae): Revision of Parapenia Species from China, with the Establishment of Three New Genera

## TL;DR

This study revises the click-beetle genus Parapenia in China, discovering six new species and three new genera based on previously overlooked reproductive structures.

## Contribution

The study establishes three new genera and highlights the importance of sclerites in the bursa copulatrix for taxonomic classification.

## Key findings

- Six new species of Parapenia were identified in China.
- Three new genera were established based on unique sclerite structures in the bursa copulatrix.
- Diagnostic tools like tables, maps, and keys were provided for species identification.

## Abstract

In this study, we revised the click-beetle genus Parapenia from China. We recognized 12 Chinese species in total, including six that are newly discovered. Two species are reported from China for the first time, and one species is treated as a synonym. A detailed study of female reproductive structures revealed plate-like structures that had rarely been noticed before in this group of beetles. These structures proved to be very reliable for identifying and separating different taxonomic groups. Based on these findings, three new genera morphologically similar to Parapenia were established. To support future work, we provided a comparative diagnostic table, distribution maps, and identification keys for these beetles in China. This research not only clarifies the true diversity of Parapenia but also demonstrates that overlooked internal structures can be essential for understanding the generic limits and how these click-beetle groups are related to each other, which is important for documenting and protecting biodiversity.

The genus Parapenia Suzuki from China is revised, with 12 species recognized, including six new species: P. fuxi sp. nov., P. nyuwa sp. nov., P. pangu sp. nov., P. ruihangi sp. nov., P. wuchaoi sp. nov., and P. zhengi sp. nov. In addition, P. sausai Schimmel and P. villosa (Fleutiaux) are newly recorded from China, and P. jagemanni Schimmel syn. nov. is synonymized with P. yunnana Schimmel. Large plate-like sclerites in the bursa copulatrix are consistently present in Parapenia and show diagnostic value for generic delimitation. Comparative morphological studies, particularly of these sclerites, justify the establishment of three new genera distinct from Parapenia: (1) Parapenioides gen. nov., including P. zidani sp. nov.; (2) Megapenia gen. nov., including M. cruciata (Bouwer) comb. nov., type species M. marginalis (Fleutiaux) comb. nov., and M. tianlongi sp. nov.; and (3) Sinopenia gen. nov., including S. significata (Schimmel) comb. nov. A comparative diagnostic table of the four genera, together with a checklist and distribution maps, is provided. Identification keys to Chinese species of Parapenia and Megapenia are also included. This study clarifies the taxonomic complexity of Parapenia and emphasizes the overlooked significance of sclerotized structures in the bursa copulatrix for distinguishing genera within Dimini.