Exploring species diversity in Tanytarsus (Diptera: Chironomidae) with almost 1600 DNA barcodes

Tanytarsus van der Wulp, 1874, occurring in all types of water, is the most species-rich genus of tribe Tanytarsini within the Chironomidae with more than 400 species worldwide. In this study, we test the effectiveness of the standard 658bp barcode fragment from the 5’-end of the mitochondrial cytochrome c oxidase 1 gene (COI) in differentiating the species of Tanytarsus. The results show that species of Tanytarsus are well differentiated by DNA barcodes, enabling the identification of characteristic morphological forms and association of life stages. The Neighbor joining tree based on 1571 DNA barcodes currently available to us in the Barcode of Life Data Systems (BOLD) comprises 133 well separated clusters representing 69 named, 17 unnamed, 31 unidentified morphological species of Tanytarsus. Among the named species, DNA barcodes have revealed cryptic diversity in several complexes. In geographically separated populations of the Tanytarsus chinyensis species group for instance, overlapping variation in morphological characters are inconsistent with the variation and deep divergence observed in mitochondrial DNA sequences. Species of the Tanytarsus gregarius group on the other hand, show significant variation in morphological characters with less divergence observed in DNA barcodes.