Abstract:The mitochondrial COI barcoding region of 14 individuals from two Mecopoda species with Folmer primers were amplified. All M. elongata COI fragments were 658 bp in length, without stop codons or indels. Due to the serious sequence ambiguities caused by direct sequencing, 85 clones were sequenced from eight M. niponensis individuals, with sequence lengths ranging from 580 to 662 bp. Among these, 20 of the clones were distinct nuclear sequences of mitochondrial origin, numts(four clones with stop codons, 15 clones with indels, one clone was frameshift), and 38 clones contained point mutations that caused two or more amino acid sequence differences as compared with the orthologs. The Kimura 2-parameter(K2P)model was adopted to calculate genetic distance, and the results indicated that the genetic distances among M. elongata individuals varied from 0 to 0.008. Among M. niponensis, intra-individual clones ranged from 0 to 0.143(inclusive of numts)or 0 to 0.083(exclusive of numts), and the inter-individual distance ranged from 0.030 to 0.051(exclusive of numts). The genetic distance between the two Mecopoda species was 0.077. Moreover, the neighbor-joining(NJ)phylogenetic tree based on the Kimura 2-parameter distances indicated that all the M. elongata individuals grouped together with high confidence(99%), and the real COI sequences and numts of M. niponensis clustered into several groups. These results indicate that numerous independent nuclear integration events in M. niponensis were scattered at various time points, which suggests a continuous process of numt generation.