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

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.