3.4 OTU delineation based on DNA barcodes using ABGD
ABGD software was utilized to delineate 189 morphological species and in total, 1227 sequences with the assignments for intraspecific divergence (p) values between 0.001 and 0.100. The results included two cases: initial partition and recursive partition. As revealed in Part II (Supporting information), 1227 samples were divided into 227 groups (p value: 0.0028-0.0077) and 190 groups (p value: 0.0129-0.0599). ABGD analysis of the whole sequencing data derived a total of 190 OTUs (Operational taxonomic units) with a prior intraspecific divergence of Pmax = 0.0599. Therefore, we chose relatively stable initial results to compare with those of morphological identification. We found that A. montanus and D. gueriniformed into two different groups, whereas Chironomus s p. XJ andC. heterodentatus , P. bullum and P. laetum ,Diamesa sp. XJC and Diamesa sp. XJB clustered into the same group, respectively.