Abstract: 【Aim】 This study aims to estimate and verify the roles of genitalia of tabanids in taxonomy with species from Hokkaido, Japan. 【Methods】 Samples of tabanid adults from Hokkaido soaked in physiological saline were dissected in petri dish by needle and tweezers under a binocular microscope and drawn. The morphological characteristics of the tergites 9 and 10, the cercus, sternite 8, the spermathecae, the spermathecal duct and the genital fork were observed and presented. 【Results】 In total 38 species of 3 subfamilies and 7 genera of tabanids have been recorded from Hokkaido. The main features of the female genitalia of 24 species of 3 subfamilies and 6 genera of tabanids in Hokkaido were observed and described here. There are the differences at the subfamily level. However, among genera, it is difficult to establish a way to determine the common points. Among species, similarities are seen only within the genus Chrysops. In other genera, the species are diversified. Consequently, for subfamily-level classification, the characteristics of tergite 9, sternite 8 and the spermathecae are enough for separation; while for genus and species-level classification, the combined characteristics of tergite 9, tergite 10, the cercus, sternite 8, the spermathecae, the spermathecal duct and the genital fork must be compared. Keys to female genitalia of tabanids are provided. 【Conclusion】 Genitalia is a critical characteristic to classification in Tabanidae as in many other insects, which is significant to facilitate the development of taxonomy and phylogenesis. This is the first systematic study on the female genitalia of the tabanids in Hokkaido.

Key words: Diptera')">Diptera, Tabanidae, taxonomy, female genitalia, morphology, Hokkaido, Japan