The Eastern common groundhopper, Tetrix japonica, is a pygmy grasshopper species widely distributed in the Eastern Palearctic region, and shows a high degree of phenotypic variation. The classification of Tetrix japonica is difficult and frequently involved errors. Among the many species of Tetrigidae that have been described in China within the last decades, many synonyms of Tetrix japonica were found. The type specimens of many species deposited in the Chinese museums have been re-examined and as a result, Tetrix japonica is systematically revised. Based on the results of this review, 23 new synonyms of Tetrix japonica are proposed: Coptotettix circinihumerus Zheng & Deng, 2004, syn. nov.; Coptotettix emeiensis Zheng, Lin & Zhang, 2012, syn. nov.; Euparatettix rongshuiensis Zheng, 2005, syn. nov.; Euparatettix zayuensis Zheng, Zeng & Ou, 2011, syn. nov.; Macromotettix nigritubercle Zheng & Jiang, 2006, syn. nov.; Macromotettix yaoshanensis Zheng & Jiang, 2000, syn. nov.; Tetrix albistriatus Yao & Zheng, 2006, syn. nov.; Tetrix albomaculatus Zheng & Jiang, 2006, syn. nov.; Tetrix albomarginis Zheng & Nie, 2005, syn. nov.; Tetrix cenwanglaoshana Zheng, Jiang & Liu, 2005, syn. nov.; Tetrix cliva Zheng & Deng, 2004, syn. nov.; Tetrix duolunensis Zheng, 1996, syn. nov.; Tetrix grossovalva Zheng, 1994, syn. nov.; Tetrix jiuwanshanensis Zheng, 2005, syn. nov.; Tetrix latipalpa Cao & Zheng, 2011, syn. nov.; Tetrix liuwanshanensis Deng, Zheng & Wei, 2007, syn. nov.; Tetrix qinlingensis Zheng, Huo & Zhang, 2000, syn. nov.; Tetrix rectimargina Zheng & Jiang, 2004, syn. nov.; Tetrix ruyuanensis Liang, 1998, syn. nov.; Tetrix xianensis Zheng, 1996, syn. nov.; Tetrix xinchengensis Deng, Zheng & Wei, 2007, syn. nov.; Tetrix yunlongensis Zheng & Mao, 2002, syn. nov.; Tetrix zhoushanensis Gao, Liu & Yin, 2022, syn. nov. It is expected that there will be the discoveries of more synonyms of this and other Tetriginae species from the Eastern Palearctic.

Classification of species is commonly based on morphological, molecular, and distribution depending on the taxa. Macromotettixoides Zheng, Wei & Jiang, 2005 and Formosatettix Tinkham, 1937 are both wingless types of Tetrigidae with extremely similar morphological characteristics, and in the current taxonomic system they are placed in two different subfamilies, Metrodorinae and Tetriginae, respectively. It is difficult to clearly identify the species of these two genera by morphological characteristics, and molecular data is often needed to assist identification. Here, the complete mitogenomes of two new species were sequenced and assembled, with that of Macromotettixoides orthomargina. Molecular data of species of Formosatettix were used to test the monophyly of Macromotettixoides and to re-assess the generic characters, and also to test whether Macromotettixoides belongs to the Asian Metrodorinae or Tetriginae. Furthermore, mitochondrial characteristics were analyzed and the phylogeny of the Tetrigidae reconstructed based on mitochondrial protein-coding genes (PCGs). The results indicated that the two new species were clustered with Macromotettixoides rather than Formosatettix, and the anterior margin of the fastigium and pronotum of the two new species usually had the humeral angle different from that of Formosatettix. Therefore, after integrating morphological and molecular data, the two new species were placed in the genus Macromotettixoides, M. maoershanensissp. nov. and M. brachycornasp. nov. Finally, a phylogenetic reconstruction supported Macromotettixoides being assigned to Tetriginae rather than Metrodorinae, in contrast to the previous classification of this genus.

Considerable effort has been devoted to elucidating the phylogenetic relationships of tetrigides. However, there is still no commonly accepted phylogenetic hypothesis. Therefore, the phylogenetic relationships among some subfamilies remain unclear; e.g., Cladonotinae is a controversial group, in which the phylogenetic relationships between genera and the boundaries of some of the included genera are unclear, causing some of the taxa to be difficult to identify. Therefore, an in-depth phylogenetic analysis of Cladonotinae is urgently needed. In this study, a robust phylogenetic framework for the tetrigides was reconstructed based on the combined mitochondrial cytochrome oxidase subunit I (COI), 16S ribosomal RNA (16S rRNA), and nuclear 18S ribosomal RNA (18S rRNA) gene sequences of 25 species belonging to 16 genera of Tetrigoidea from China, which included 13 species from 8 genera of Cladonotinae. Phylogenetic inferences were performed using the combined dataset and Bayesian inference (BI) and Maximum Parsimony (MP) methods, and the phylogenetic tree of Cladonotinae was reconstructed. All inferences based on the results of the present study supported the Cladonotinae subfamily as a polyphyletic group; within the Cladonotinae subfamily, Tetradinodula, and Tuberfemurus were closely related to Tetriginae, while Austrohancockia and Gibbotettix showed a close relationship to the Scelimenidae subfamily. Additionally, a new genus and new species of the Cladonotinae subfamily are described and illustrated: Hainantettix Deng, gen. nov. and Hainantettix strictivertex Deng, sp. nov.

The mitochondrial genome (mitogenome) of Saussurella borneensis (Orthoptera: Tetrigoidea) was determined and analyzed. The complete mitochondrial genome is 16,006 bp in length, consisting of 37 genes, including 13 protein-coding (PCGs), 22 tRNA, 2 rRNA genes as well as an A + T-rich region. Ten PCGs initiated with a typical ATN codon (one with ATC, two with ATA, two with ATT, and five with ATG) and 13 terminated with complete stop codons. The overall nucleotide composition was 42.97% for A, 17.61% for C, 11.62% for G, and 27.8% for T. Phylogenetic analysis of S. borneensis fully resolved it in a basal branch sister to Tripetaloceroides tonkinensis. This data increase the bioinformatics of the Tetrigidae, and improves our understanding of the phylogenetic status of S. borneensis in the Tetrigoidea.

The mitochondrial genome (mitogenome) of the Tripetaloceroides tonkinensis (Orthoptera: Tetrigoidea) was sequenced and annotated. The complete mitogenome has a length of 16,696 bp and consists of 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a A + T-rich region. Thirteen PCGs started with typical ATN codon and ended with complete stop codons (five with TAG, eight with TAA). The overall nucleotide composition was 42.7% of A, 10.34% of G, 25.87% of T, and 21.08% of C. The phylogenetic trees in the current study confirmed that T. tonkinensis was clustered with other Tetrigoidea species, and the study would improve our understanding for the mitogenomes of Tetrigoidea.

The genus Macromotettixoides Zheng, Wei & Jiang, 2005 is reviewed. Four new species of the genus, M. daiyunshanensis Deng, sp. nov., M. curvicarina Deng, sp. nov., M. convexa Deng, sp. nov. and M. shengtangshanensis Deng, sp. nov. are described with detailed illustrations of external morphology. Two new synonyms are established: M. jinggangshanensis, syn. nov. is synonymized with M. jiuwanshanensis Zheng, Wei & Jiang, 2005; M. parvula Zha & Wen, 2017, syn. nov. is synonymized with M. undulatifemura Deng, Zheng & Yang, 2012. Additionally, an updated key to species of the genus is given.