A small step can also be a big step—first study on DNA barcoding in species delimitation of oribatid mites in Russia

Oribatid mites (Acari, Oribatida) are a large group of soil animals, with small body sizes and complex morphological structures. At present, oribatid mite species identification is essentially based on morphological characters. In this study, we collected 124 specimens of oribatid mites belonging to 110 species of 72 genera in Russia, and extracted their genomic DNA subsequently. In order to investigate whether the molecular data (DNA-barcoding marker, COI gene) and morphological classification results are consistent, we used three methods, ASAP, ABGD and GMYC, to delimit species, and calculate a maximum likelihood tree. The results indicate that COI gene fragments can be effectively used for species delimitation. There are some cryptic species identified in oribatid mites, which do not have distinct morphological differences, but diverge considerably in molecular data. Meanwhile, some formerly unidentified species could be identified through molecular means. The study enriches the molecular data of oribatid mites worldwide and provides the basis for more detailed taxonomic studies of oribatid mites in Russia. In the future, more analyses and mining of molecular data, combined with morphological analyses, will help to reveal and further understand the phylogenetic relationships of Oribatida.