Phylogenetic Analyses Of Metrodorinae(Orthoptera:Tetrigidae) Based On The Mitochondrial Genome

The subfamily Metrodorinae belongs to the Insecta,Orthoptera,Tetrigoidea,Tetrigidae.The previous molecular phylogenetic studies of Metrodorinae were still limited to morphology and individual genes,and there were few phylogenetic studies related to the mitochondrial genome as a whole.In this study,mitochondrial genomic data are determined for 28 species of Tetrigoidea,including 13 species of seven genera of the Metrodorinae.The mitochondrial genome of the Metrodorinae were characterized by bioinformatics and comparative genomics.A preliminary analysis of the phylogenetic relationships was performed between the monophyly of the Metrodorinae,their phylogenetic relationships with other closely related subfamilies,and the attribution of the species of each genus at the subfamily level in conjunction with the published mitochondrial genome data of Tetrigoidea in the NCBI(National Center for Biotechnology Information)database.Results are:(1)The mitochondrial genomes of 13 species in the Metrodorinae ranged from14,615-15,412 bp in length.The 13 sequences measured are identical in gene order and orientation,both containing 37 coding genes.Gene rearrangements are not observed,and spacer regions and gene overlaps are present.All PCGs(protein coding genes)start codons are ATN except for NAD6,which is TTG,and the stop codons are TAA/TAG/T/A.(2)Analysis of the base composition of Tetrigoidea shows that the A+T content is greater than the G+C content,with the A+T content ranging from 68.6% to 76.9%.The Phe,Leu,Ile and Met are the first four frequent amino acids,and ATT,TTT,TTA and ATA are the first four frequent codons in Tetrigoidea.The genetic distance analysis found that ATP8 is the fastest evolving gene,COI is the most conserved gene in the mitochondrial genome of Tetrigoidea.(3)A phylogenetic tree was constructed using Maximum Likelihood(ML)and Bayesian Inference(BI)methods based on five different datasets of 57 species from six subfamilies of Tetrigoidea,with Oxya intricate(St?l,1861)(Acridoidea)and Mirhipipteryx andensis Günther,1969(Tridactyloidea)as outgroups.The topology of the phylogenetic trees constructed by both methods is consistent for each dataset.The results show that: monophyly is supported for Tetrigoidea;The species of the Metrodorinae mixed with species of the Scelimeninae,the Cladonotinae and the Tetriginae;the Metrodorinae is polyphyletic;the monophyletic Batrachideinae is the most basal branch of the ingroup;the Tripetalocerinae represents the subbasal branch of the ingroup.In the generic level,six species of Bolivaritettix are grouped together in a monophyletic group,but Bolivaritettix circocephalus Zheng,1992 is nested within Cotysoides;Systolederus is a monophyletic group that forms a sister group with Teredorus.In the specific level,Xistra strictivertex Zheng ? Ou,2010 forms a sister group with Zhengitettix curvispinus Liang,Jiang ? Liu,2007;Mazarredia convexa Deng,Zheng ? Zhan,2010 forms a sister group with Loxilobus prominenoculus Zheng? Li,2001;Macromotettixoides truncata Mao,Li ? Han,2020 forms a sister group with Hyboella nigrimaculata Li,Han ? Mao,2019;Cotysoides yunnanensis Zheng ?Mao,2010 is sister to Bolivaritettix circocephalus,and the genetic distance between them is relatively short.(4)Morphological analysis suggests that: the “narrowed vertex” is the homologue of the genera Systolederus and Teredorus,and the “truncate” and “rounded” shapes of the posterior angles of lateral lobes of pronotum are their autapomorphies.The “head above the pronotum and vertex narrow” is the homologue of the genera Xistra and Zhengitettix,and the “truncate” and “spine-like” shapes of the posterior angles of lateral lobes of pronotum are their autapomorphies.The “eyes above the pronotum and vertex narrow” is the homologue of the genera Mazarredia and Loxilobus,and the “truncate”and “acute” shapes of the posterior angles of lateral lobes of pronotum are their autapomorphies.The genera Cotysoides and Bolivaritettix are both of monophyletic groups.The position of the antennae is the basis for the distinction between the genera Cotysoides(antennae between lower third of eyes)and Bolivaritettix(antennae between lower margin of eyes).The Bolivaritettix circocephalus should be moved to the genus Cotysoides to become the new group Cotysoides circocephalus Zheng,1992 comb.nov.,and the Criotettix ruiliensis should be moved to the genus Cotysoides to become Cotysoides ruiliensis comb.nov..