# Molecular Techniques and Ecological Data for Taxonomically Difficult Groups: A Case Study of a Morphologically Variable New Species in the Genus Chrysobothris (Coleoptera: Buprestidae)

## TL;DR

This paper describes a new beetle species in the Chrysobothris genus from southern China, using DNA barcoding and ecological data to resolve taxonomic confusion among morphologically variable specimens.

## Contribution

The study integrates molecular and ecological data to delineate a new species within a taxonomically challenging beetle group.

## Key findings

- Four morphologically distinct Chrysobothris specimens from southern China were confirmed as a single new species via COI barcoding.
- The new species, Chrysobothris borealina, is genetically distinct from C. violacea and shows ecological differentiation in elevation and phenology.
- A rare mite attachment was observed on a female specimen, suggesting potential ecological interactions.

## Abstract

Morphological characters of beetles can exhibit considerable variation, even within a single species. Within a Chrysobothris group from southern China, four morphotypes were suspected, raising the possibility that they represented multiple species or subspecies. By using COI barcode sequencing, we determined that all forms belong to the same species, which is genetically distinct from its closest relative species, C. violacea Kerremans, 1892. Herein, we describe and illustrate a new species, Chrysobothris borealina Huang, Wu & Song, sp. nov. Key morphological characters are summarized, ecological notes are provided, and the presence of mite attachment on one female specimen is reported.

Morphological characters of beetles can differ greatly, even within a single species, necessitating the integration of molecular techniques and ecological data for accurate taxonomical delineation, particularly within taxonomically challenging groups. Chrysobothris, a world-distributed genus of considerable size with a homonymy rate exceeding 1/5, frequently presents ambiguities in species boundaries. In this research, a series of Chrysobothris specimens collected from southern China were segregated into four sharply contrasting external morphotypes. A taxonomic ambiguity was initially posed: whether they represented several species, intraspecific polymorphism within a single species, or geographic/intraspecific variants of the similar species Chrysobothris violacea Kerremans, 1892. COI barcoding and phylogenetic analyses supported the conspecificity of these morphotypes and confirmed their distinction from C. violacea at the species level. Based on integrated evidence, we describe these specimens as Chrysobothris borealina Huang, Wu & Song, sp. nov., provide diagnostic characters with illustrations, and compare the new species with C. violacea. The species occurs in mid- to high-elevation pine and pine–broadleaf mixed forests and differs from C. violacea in both elevational range and phenology, indicating potential ecological differentiation. Additionally, we document a rare instance of a nymphal parasitengone mite (cf. Erythraeidae) attached to one female specimen.