Molecular and Morphological Evidence Reveal Lithocarpus dahuensis and L. konishii (Fagaceae) Are Conspecific

Abstract— Taxonomic uncertainties in rare species can hinder effective conservation planning and prioritization. Lithocarpus dahuensis was described in 2023 as an endemic species based on a single population from Minhou County, Fujian Province, China, and was assessed as an endangered species. However, its morphology closely resembles that of L. konishii , raising doubts about its taxonomic distinctiveness. To clarify this taxonomic ambiguity, we used whole-genome resequencing data from 20 samples, including 3 of L. dahuensis and 6 of L. konishii , to reconstruct the phylogenomic tree. In parallel, we examined leaf morphology using geometric morphometrics and a neural network classifier to evaluate morphological differentiation between the two taxa. Phylogenomic analyses revealed that all L. dahuensis individuals formed a small lineage nested within L. konishii , and morphological analyses showed substantial overlap in leaf traits. These findings demonstrate that L. dahuensis is conspecific with L. konishii and should be treated as its synonym. The Minhou population thus represents the northernmost records of L. konishii , and its presence constitutes a new distribution record for Fujian Province. Given the overall rarity and significant geographic isolation of L. konishii populations, we recommend both in situ and ex situ conservation efforts for the species.