Abstract: DNA barcoding is a useful tool for species identification using standardized genomic DNA fragments. The genus Amentotaxus, consisting of five or six species, is confined to South China, Northeast India, Laos, and Vietnam. All species have been assessed as globally or nationally threatened. However, there is uncertainty about the number of species involved, especially in the border areas of southern China, northern Vietnam, and Laos. We selected five DNA barcodes (rbcL, matK,trnH-psbA, trnL-F, and internal transcribed spacer (ITS)) to evaluate their discrimination ability in this genus, and to investigate the current taxonomy of Amentotaxus. Our results indicate that all the selected barcoding regions showed a high level of universality for PCR and sequencing. When six species are recognized, the nuclear ribosomal DNA region ITS and the chloroplast DNA region trnL-F used on their own provided the highest identification success (60%). Two barcode combinations that included either ITS or trnL-F had the same species discrimination ability. Combinations using additional barcodes did not improve the species identification success. When only five species are recognized, with A. hatuyenensis T. H. Nguyen treated as a synonym of A. yunnanensis H. L. Li, the discrimination rate rises to 100%. Our results also indicate that recent collections from Yunnan province, China, Lao Cai province, Vietnam, and Laos may represent a potential new species. The findings from this study will be very useful for the formulation of appropriate conservation strategies for threatened Amentotaxus species in national and trans-boundary regions.

Key words: Amentotaxus, biodiversity conservation, DNA barcoding, new species discovery, species discrimination