Hidden biodiversity revealed by DNA barcoding in black fly genus Simulium

Background & objectives: The black fly genus Simulium Latreille is one of the most important medical insect group of the family Simuliidae (Diptera) and many species of this genus are important pests of human and animals, while some of them also represent vectors of pathogens. Correct species identification is essential to the implementation of control measures for species of medical or agricultural importance. Methods: In this study, the usefulness of DNA barcoding was discussed in distinguishing species of Simulium. Results: Analysis showed hidden biodiversity, usually referred to in Simuliidae as cryptic species, which was detected in 15 species. Firstly, intraspecific divergences of eleven species was unexpectedly high and the maximum distances of them ranged from 5.1-16.8%. Based on the differential of K2P (Kimura 2-Parameter) distances, sequences were subdivided into two or three groups, respectively. Secondly, extremely low interspecific divergences were detected in eight groups of species, and shared haplotypes were also found among them. Furthermore, the subdivision within species and shared haplotypes among some species were all supported by the NJ (Neighbour-Joining) analysis. Interpretation & conclusion: Our results confirmed that DNA barcoding was a powerful tool for revealing hidden species diversity of black flies. Further work is needed to reveal ambiguous species delimitation in some problematic species groups.