Discovery of a highly variable bug killing fly species, Clytiomya continua (Diptera: Tachinidae: Phasiinae), in Korea with discussion on its systematic status

Abstract At present, the genus Clytiomya of the tribe Gymnosomatini includes four Palaearctic species, which exhibit high intraspecific variability. While studying Korean members of the bug-killing fly subfamily Phasiinae, we discovered C. continua for the first time in the Korean Peninsula. This is also the first record of Clytiomya from Korea. Our collection of C. continua includes over 150 freshly frozen individuals showing intraspecific variation as well as sexual dimorphism. This provided us an opportunity to examine their variability and species status. In fact, we initiated this study assuming the presence of multiple species. We examined the morphological variation, and analyzed the DNA barcode sequences of individuals, covering as many morphological variants as possible to distinguish any biological species. DNA barcoding analysis of 21 Korean C. continua sequences and over 180 phasiine sequences retrieved from the Barcode of Life Data (BOLD) Systems revealed that C. continua is a highly variable species with extreme sexual dimorphism. In both sexes, bright golden and dark dull individuals can be easily confused as two or more distinct species when there are only a few individuals available. Based on the examination of the Korean individuals, we provide taxonomic diagnosis and description. Moreover, DNA barcoding analysis demonstrated the close relationship between the genera Clytiomya and Ectophasia, although they both are not monophyletic. Further study is needed to clarify the species limits of the remaining three Clytiomya species.