DNA barcoding and geometric morphometry of tabanid flies (Diptera: Tabanidae) in Thailand and a new record of a Thai horse fly.

Tabanid flies are gaining high medical and veterinary importance due to their role as a vector of many pathogens. In the present study, a total of 3760 female tabanid flies were collected from Narathiwat and Phayao provinces of Thailand. All were identified using the morphological method, DNA barcoding and wing geometric morphometric (WGM) analysis. Eight species were identified, and among them, Tabanus tenens is a new recorded Thai horse fly. Morphologically, 2178 and 1559 females from Narathiwat and Phayao were identified at the species level, including Chrysops dispar, Chrysops fasciatus, Tabanus griseilineis, Tabanus rufiscutellatus and Tabanus minimus. The other 23 females were identified at the level of the genus (Tabanus spp.) only. Among these, DNA barcoding was further identified as Tabanus tenens, Tabanus rubidus and Tabanus striatus. The landmark-based WGM analysis was used to differentiate the samples from Narathiwat, and the results showed the efficacy of this approach in differentiating the four species of tabanids, achieving an overall accuracy score of 99%. Additionally, the data derived from wing landmarks of samples collected in Narathiwat were used as reference materials for identification of the tabanid fly collected from Phayao, and the finding revealed efficacy of the reference materials. Together, this study demonstrated that DNA barcoding is a reliable tool for the identification of tabanid fly species, while WGM analysis could be a complementary tool. The barcode sequences and WGM data generated in this study can serve as a valuable reference material to identify new field samples from other regions of Thailand. Altogether, this study updated the species list of tabanid flies in Thailand, particularly in the Narathiwat and Phayao provinces, using various integrative identification tools.