Abstract: Up to now, the reports about the complete mitochondrial genome of katydids and their corresponding molecular evolution are still limited. In this study, the mitochondrial genomes (mitogenome) of two longlegged katydids, i.e., Mecopoda elongata and M. niponensis, were sequenced using the LPCR combined with the sub-PCR technology. The results showed that the mitogenome sequence of M. elongata is 15 284 bp in length, haboring the A+T content of 71.8% (GenBank accession no.: JQ917910), while M. niponensis is 15 364 bp in length with the A+T content of 72.4% (GenBank accession no.: JQ917909). The differences in their mitogenome sizes can account for the size variations in their control regions (294 bp for M. elongata and 393 bp for M. niponensis). The organization and gene content of both two Mecopoda mitogenomes are identical with those of other studied Tettigoniidae species. A few of noteworthy larger non-coding regions are shared by both species: the first is between trnA and trnR (63 bp in M. elongata, and 68 bp in M. niponensis), the second between trnQ and trnM (55 bp in M. elongata, and 26 bp in M. niponensis), and the third between trnS^UCN and nad1 (21 bp in both species). In both Mecopoda species, there are overlaps between trnC/trnW (8 bp), atp8/atp6 (7 bp) and nad4L/nad4L (7 bp). AT nucleotide composition bias of both Mecopoda mitogenomes is also reflected in the codon usage of NNU or NNA bias. In both Mecopoda mitogenomes, all protein-coding genes (PCGs) start with the typical ATN initiator codon expcept for nad1 and nad2 with TTG and cox1 with ATGA. All tRNAs in both Mecopoda species have the typical clover leaf structure except for trnS^AGN. Some unmatched base pairs occur in both Mecopoda species, and overwhelming majority of them are G-U pairs, indicating that G-U is a normal base-pairing model in insect mitogenomes. Another unusual feature is the relatively lower A+T content of control region (CR) compared with other regions of the mitogenomes, underlining the fact that high A+T content is not characteristic of this control region. The results of this study provide some valuable molecular data for clarifying the intra-subfamilies phylogenetic relationship in Tettigoniidae.

Key words: Orthoptera')">

Orthoptera, Tettigoniidae, Mecopoda elongata, Mecopoda niponensis, mitochondrial genome, sequence analysis