Factors affecting the accuracy of molecular delimitation in minute herbivorous mites (Acari: Eriophyoidea)

Single‐locus molecular delimitation plays a key role in meeting the need to expedite the exploration and description of the species on our planet. Multiple methods have been developed to aid data interpretation over the past 20 years, but species delimitation remains difficult due to their varying performance. In this study, we examine the accuracy of five widely used delimitation methods (i.e. BIN, ABGD, ASAP, GMYC and mPTP) in analysing 63 empirical data sets that included 1850 mitochondrial COI sequences derived from eriophyoid mites assigned to 456 morphospecies. Our results establish that all five methods resolve approximately 90% of morphospecies. We investigated some factors which might affect the species delimitation results, that is taxonomic rank, number of haplotypes per species, mean number of host plants per species, and geographical distance among sampling sites. We found complex interactions between these factors which affected delimitation effectiveness. An increase in haplotype number negatively affected delimitation accuracy, while increased geographical distance improved delimitation accuracy. BIN was influenced by the number of host plants per species as cryptic speciation linked to host plant usage might be prevalent in eriophyoid mites, while ABGD was not significantly impacted by other factors. Our results highlight multiple factors that affect molecular species delimitation and underline the value of employing multiple analytical approaches to aid species delimitation.