Checklist of Water mites in Mexico. Historical background and DNA barcoding perspectives

Water mites are the most ubiquitous, abundant, diverse, and ecologically important group of arachnids in all freshwater environments. In Mexico, despite being a megadiverse country, only 271 species have been recorded so far since 1873. This is probably due to the scarcity of taxonomists in the country or the inherent complex morphology of this group, which challenges its systematics and its integration into other research studies. Molecular identification has been highly useful for practical applications of these organisms, while taxonomic identification work continues. Until now, a species checklist and reference information about water mites diversity and distribution in Mexico is lacking. In this work, we compiled species described or recorded in Mexico and provided preliminary data for a COI barcode library of the water mites in the country. This checklist includes 271 species from 25 families and 61 genera. In addition, the COI barcode library is supplied in a public dataset from the BOLD database (boldsystems.org); it contains 794 sequences corresponding to 103 BINs or putative species, of which only five of them have been identified to the species. We predict that the discovery of hidden diversity of mites will continue and improve after the use of integrative taxonomy tools. Also, their value as indicators of water quality will be re-evaluated, helping in the conservation of freshwater environments and the evaluation of the global warming impact.