Material and methods

The institutions cited in the present paper are indicated by the following abbreviations:

AHU Anhui University, Hefei, China.

MNHN Museum national d’Histoire naturelle, Paris, France.

SHNU Shanghai Normal University, Shanghai, China.

Terminology follows Holloway (1960, 1961). Measurements are given in millimetres (mm). Body length was measured from the apex of the mandibles to the elytral apex.

Morphological observations and measurements were performed using an Olympus SZX7 stereomicroscope. Photographs of the adult specimens and male genitalia were taken with a Canon 5Ds digital camera equipped with a Canon MP-E 65 mm f/2.8 1–5× Macro Photo Lens.

The distribution map of the genus Ceruchus was generated in ArcGIS Pro v. 3.7 (Esri, Redlands, California, USA). Geographic information was compiled from published records in Huang et al. (2011), Huang and Chen (2017) and Huang et al. (2020), together with specimen records from our laboratory collections and field survey data. To reduce spatial autocorrelation and visual clustering, the occurrence records were spatially thinned, retaining only one record per species within a 5 km radius. Digital elevation model (DEM) data at a spatial resolution of 30 arc-seconds (c. 1 km) from the WorldClim 2.1 database (Fick and Hijmans 2017) were used as the topographic base map, and provincial administrative boundaries of China were overlaid for geographic reference. The occurrence data underlying this study were deposited in the Global Biodiversity Information Facility (GBIF) and are available at https://doi.org/10.15468/jzbytm (Huang 2026).

For molecular comparison, we newly sequenced two specimens, representing the new species and its sympatrically distributed close relative, Ceruchus niger Boucher & Král, 1997. New sequences were submitted to General Biol (Anhui) Co., Ltd (Chuzhou, Anhui, China) for genomic DNA extraction, library preparation, and sequencing. Total genomic DNA was extracted from fresh tissue, and whole-genome paired-end short-read sequencing was performed on an Illumina platform, generating 150 bp paired-end reads and approximately 10 Gb of data per sample. Mitochondrial candidate scaffolds were recovered from the whole-genome reads using GetOrganelle v. 1.7.7.1 under the animal mitochondrial mode. The standard DNA barcode fragment of mitochondrial cytochrome c oxidase subunit I (COI) was identified from the mitochondrial candidate scaffolds by BLAST searches against reference sequences and subsequently extracted for genetic distance analysis and tree reconstruction. Additional COI sequences of Ceruchus species were downloaded from GenBank. The COI sequence of Sinodendron yunnanense was extracted from its mitochondrial genome sequence downloaded from GenBank and used as the outgroup. All sequences were aligned using MAFFT v. 7.526 with automatic direction adjustment. Pairwise genetic distances among the sampled Ceruchus species were calculated under the Kimura 2-parameter model. A maximum-likelihood tree was reconstructed in IQ-TREE v. 3.1.3 using the best-fit substitution model selected by ModelFinder. Branch support was assessed using 1000 ultrafast bootstrap replicates.

Information on all sequences used in this study is summarized in Table 1.

Species | Sample Locality | GenBank Accession | Source
Ceruchus ahualuo sp. nov. | Yunnan, China | PZ603445.1 | This study
Ceruchus niger | Yunnan, China | PZ603446.1 | This study
Ceruchus lignarius | Gunma, Japan | AB427048.1 | GenBank
Ceruchus minor | Sichuan, China | LC511010.1 | GenBank
Ceruchus minor | Sichuan, China | LC511011.1 | GenBank
Sinodendron yunnanense | Yunnan, China | KP735804.1 | GenBank