Mitogenome-Based Phylogenetic Analysis of Two Ball-Rolling Dung Beetles, Gymnopleurus mopsus and Gymnopleurus geoffroyi (Coleoptera: Scarabaeidae: Scarabaeinae), with Notes on the Phylogenetic Relationships of Scarabaeinae

The tribe Gymnopleurini is a well-known group within Scarabaeinae, characterized by its diurnal ball rolling behavior. Although mitochondrial genomes have been reported for numerous Scarabaeinae species, those of Gymnopleurini remain unexplored. In this study, we document for the first time the mitochondrial genome sequences of two ball-rolling dung beetles, Gymnopleurus mopsus (Pallas, 1781) and Gymnopleurus geoffroyi (Fuessly, 1775), from the tribe Gymnopleurini and infer the tribe's position within Scarabaeinae, whose phylogenetic relationships remain largely unresolved. Their mitochondrial genomes are circular DNA molecules, 15,591 and 15,460 bp in size, respectively, and consist of 37 genes, with an identical gene order in Scarabaeinae. Mitochondrial phylogeny, based on the sequences of 13 protein-coding genes (PCGs) from 72 Scarabaeinae species, recovered monophyly of Scarabaeinae and a sister relationship between Gymnopleurus (Gymnopleurini) and Sarophorus. This finding is the first to suggest a potential sister relationship between two groups, but like previous studies, the lack of strong synapomorphic characters implies further phylogenomic analysis is needed to confirm their relationship. Notably, the monophyly of the Onthophagini + Oniticellini lineage was supported, reflecting its biogeographic history and highlighting the need for a taxonomic revision of this species-rich and cosmopolitan group, incorporating additional suprageneric groups. The mitochondrial genome information of two Gymnopleurini species, G. mopsus and G. geoffroyi, not only helps fill the gap in the missing mitochondrial genome data for the Gymnopleurini tribe but also contributes to future conservation efforts by providing insights into the genomic diversity and population structure of these two threatened species.