Future prospects and lessons learned from nine years of Chironomidae (Diptera) DNA barcoding

Background: The family Chironomidae has about 6200 species described world-wide and is among the most widely distributed families of Diptera. Chironomids are found in almost all kinds of terrestrial and aquatic habitats but are particularly species rich and abundant in freshwaters. Many species have specific habitat requirements, and chironomids are therefore well suited for biological monitoring as well as research projects focused on evolution and biogeography. However, the full potential remains unleashed as many species are difficult to identify, and a large number still is undescribed. DNA barcoding of Chironomidae therefore represents a great tool for the advanced use of non-biting midges in research and nature management. Results: We summarize our work on DNA barcoding of Chironomidae over the last 9 years based on more than 6000 records of 900 named species (1267 BINs) in BOLD. Focus is on analytical success, the importance of vouchers, association of life stages, detection of cryptic diversity, and the lack of genetic variation. Significance: A DNA barcode library provides a common base for species interpretation and paves the way for a broader use of Chironomidae in environmental studies and biosystematics.