DNA barcoding of Naididae (Annelida, Oligochaeta) based on COI and ITS2 genes in China

Exploring the effectiveness of DNA barcoding in species identification is prerequisite for biodiversity conservation and environmental monitoring. Aquatic oligochaete could serve as an excellent indicator in aquatic monitoring programs. However, few studies have examined the effectiveness of DNA barcoding in these specific organisms. The mitochondrial COI gene and nuclear ITS2 gene of 83 specimens belonging to 36 species of 18 genera were sequenced in this study. The results showed that there was a barcode gap between species of Naididae, and the intraspecific genetic distances of each species were smaller than interspecific genetic distances. The classification results of ABGD (Automatic Barcode Gap Discovery) were consistent with those of morphological identification except for Tubifex tubifex and Lumbriculus variegatus . All species were successfully distinguished in the phylogenetic tree based on ITS2 gene, which was coincident with morphological result. Our results provided evidence that DNA barcoding can be used as an effective and convenient tool for species identification of the family Naididae and even aquatic oligochaete.