DNA barcoding has been proposed as a rapid and reliable tool for animal identification and species delineation. The 5’ end of the mitochondrial cytochrome c oxidase I gene (COI-5P) was sequenced for 318 specimens of 55 mantis species. Of these, 44 species had not been sequenced before, thus being new COI-5P barcode sequences to science. Another 61 COI-5P barcode sequences comprising five species were retrieved from the Barcode of Life Database (BOLD; www.boldsystems.org). Five species delimitation algorithms were employed to sort barcode sequences into Molecular Operational Taxonomic Units (MOTUs), namely the distance-based Barcode Index Number (BIN) System, Generalized Mixed Yule Coalescent (GMYC), a Java program that uses an explicit, determinate algorithm to define Molecular Operational Taxonomic Unit (jMOTU), Assemble Species by Automatic Partitioning (ASAP), and Bayesian implementation of the Poisson Tree Processes model (bPTP). All species, except Hierodula chinensis Werner, 1929, were recovered as monophyletic on the neighbor-joining (NJ) tree. For the final dataset, 379 COI-5P barcode sequences were assigned to 68 BINs. Fifty-five out of 68 BINs obtained were new to BOLD. The low level of BIN overlap with other nations highlights the importance of constructing a regional DNA barcode reference library. The algorithms ASAP, jMOTU, bPTP, and GMYC clustered barcode sequences into 32, 58, 68, and 60 MOTUs, respectively. All species delimitation algorithms (except ASAP analysis) split Anaxarcha sinensis Beier, 1933, Anaxarcha zhengi Ren & Wang, 1994, H. chinensis, Spilomantis occipitalis (Westwood, 1889), Titanodula formosana Giglio-Tos, 1912 into more than one MOTUs. All algorithms merged Hierodula sp. BCM-2019 and H. chinensis into the same MOTU, as for Tenodera aridifolia Stoll, 1813 and Tenodera sinensis Saussure, 1871. More accurate identification results need to be supplemented by detailed morphological classification.
