The complete mitochondrial genomes of Xenostrongylusvariegatus and Epuraea sp. were sequenced and analyzed. The total genome lengths are 17,657 and 16,641 bp, with an A+T content of 77.2% and 76.4%, respectively. Each mitochondrial genome consists of 37 coding genes and a non-coding (AT-rich) region. All protein-coding genes (PCGs) start with the standard start codon, ATN, and end with complete stop codons, TAA and TAG, or an incomplete stop codon, T. All tRNAs can be folded into the typical clover-leaf secondary structure, with the exception of trnS1 in both species with a reduced dihydrouridine (DHU) arm. The AT-rich region has tandem repeats differing in both number and length. Genetic distance and Ka/Ks analyses show that nad6 has a higher variability and more rapid evolutionary rate than other PCGs. Both maximum likelihood and Bayesian inference phylogenetic analyses based on 13 PCGs and 2 ribosome DNAs (rDNAs) agree with the previous phylogenies in supporting the Nitidulidae monophyly and the sister-group relationship of Kateretidae + (Monotomidae + Nitidulidae).

Beetles (Coleoptera) represent one of the most diverse insect groups and play vital ecological roles, yet their accurate identification is often challenging due to morphological similarities among taxa. DNA barcoding has emerged as a powerful and reliable tool for species-level identification and biodiversity monitoring. In this study, we established a local DNA barcode reference database for beetles in the Liancheng Nature Reserve, Gansu Province, China. From May to August 2024, beetle specimens were collected and identified using both morphological traits and DNA barcoding. Three species delimitation methods—Automatic Barcode Gap Discovery (ABGD), Assemble Species by Automatic Partitioning (ASAP), and Bayesian Poisson Tree Processes (bPTP)—were employed as complementary analytical tools, and phylogenetic relationships were inferred from cytochrome c oxidase subunit I (COI) sequences. A total of 164 COI sequences (650 bp) were obtained, representing 126 beetle species from 95 genera and 20 families. DNA barcoding successfully resolved morphologically ambiguous taxa, with many sequences reported here for the first time. Phylogenetic analysis revealed that species within the same genus formed cohesive clades before clustering at the family level, confirming the species-level discriminative power of the COI gene. Collectively, these findings demonstrate that COI-based DNA barcoding is a powerful complement to traditional taxonomy. The establishment of this preliminary reference database provides a valuable molecular resource for beetle identification and a practical tool to support biodiversity conservation, resource management, and long-term monitoring in the Liancheng Nature Reserve.

Mitochondrial genomes provide powerful insights into insect phylogeny and molecular evolution, aiding in the clarification of complex taxonomic relationships. Within the swallowtail butterfly subfamily Parnassiinae (Lepidoptera: Papilionidae), an insect group of significant environmental and economic importance, essential aspects of phylogenetic positioning remain unresolved. This study presents the first sequencing and annotation of the complete mitogenome for Parnassius stubbendorfii from two geographically distinct populations in Gansu Province, China. Both mitogenomes are circular, double-stranded molecules, measuring 15,377 bp and 15,348 bp in length, each encoding 37 standard mitochondrial genes: 13 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes, and an A + T-rich control region. The gene arrangement is highly conserved and typical of Lepidoptera. Phylogenetic analyses based on both the 13 PCGs and the complete set of 37 mitochondrial genes supported the placement of Parnassiinae as a subfamily within Papilionidae, with Parnassini and Zerynthini identified as two distinct clades within Parnassiinae. Notably, tree topologies derived from the 13 PCGs alone exhibited slight deviations from those based on the full mitogenome, underscoring the need for expanded mitogenomic data across Papilionidae to further refine evolutionary relationships.

Two new Pocadius species, P. tenebrosus sp. nov. and P. zhangjiajieensis sp. nov., are described and illustrated from southwestern and south-central China. Diagnostic characters of the new species and related species are discussed.

Two new species of sap beetles, A. (A.) similinconspicua sp. nov. and A. (A.) shizhuica sp. nov., of the subgenus Aethina Erichson, 1843 are described and illustrated from southwestern China. And four new species, A. (A.) cyaneipennis Grouvelle, 1903, A. (A.) dubitabilis Kireitshuk, 1986, A. (A.) kirejtshuki Jelínek, 1995, and A. (A.) lindskogi Jelínek & Kirejtshuk, 1986 are recorded for the first time from China.

Three new species of sap beetles in the genus Soronia Erichson (S. expansa sp. nov., S. magnipunctura sp. nov. and S. xiangxiyuanica sp. nov.) are described and photographed. Two newly recorded species from China, S. gratiosa Kirejtshuk, 1988 and S. grisea (Linnaeus, 1758), are photographed and this new range extension is documented. A key to species of the genus Soronia in China is provided.