Molecular Phylogeny Of Odontolabis From The Oriental Region(Coleoptera:Lucanidae:Odontolabini)

Odontolabis Hope belongs to the tribe of Odontolabini(Coleoptera:Lucanidae).About 50 species(including subspecies)are known in this genus merely distributed in the Oriental Region.Among of the Odontolabis stag beetles sexual dimorphism,male polymorphism and color pattern are presented intraspecifically,especially the male mandibles exhibit remarkable variaitons,in contrast,the morphological traits look very similar interspecifically,including the characters of male and female genitalia.Therefore,the systematics of Odontolabis is confused caused by these intraspecific variations and interspecific similarited during the morphological taxonomy studies.In particular,the species delimitation remains to be solved for several species complexes.The molecular phylogeny of Odontolabis is needed to be explored for discussing these systematic problems.In this study,we selected three mitochondrial genes COI,16S rDNA,Cytb and two nuclear genes Wingless and CAD,using RAxML/raxmlGUI1.5b1 and MrBayes software,using the maximum likelihood method(ML)and Bayesian Inference(BI)method,reconstructed the phylogenetic trees of Odontolabis based on 18 species,and the O.sinensis complex about 62 individuals(including O.sinensis with the narrowly red elytral spot,O.fallaciosa with the largely yellow elytral spot and a transition form between them).Three methods including ABGD,GMYC and PTP were used for species delimitation.Additionally,we obtained the complete mitochondrial genome of O.fallaciosa using the NGS for exploring the mitochondrial evolution in this genus.The main results of the study are as follows:(1)We have altogether obtained 480 gene sequences,including 112 COI sequences,79 16S rDNA partial sequences,68 Cytb sequences,118 Wingless partial sequences,103 CAD sequences.(2)The phylogenetic reconstruction strongly supported that Odontolabis is monophyletic,and sister to Neolucanus.In Odontolabis,the toplogy showed that genetic divergences of these representative speices were highly related to their geographic distributions:some species from the islands in Southeast Asia formed a"Insular clade",and others with the discontinuous distribution between the continent and the islands formed a "Insular-continental clade".This phylogeny could imply that the deeply correlation between the genetic divergence and geographic distributions.In addition,the systematic inconsistencies of different individuals arised among a same species due to lack of 16S rDNA or/and CAD genes.This unsatisfying phenomenon could be caused by a large deal of genetic information absence carried by the two important genes.(3)The phylogeny analysis of O.sinensis complex revealed that there were three branches:those geographic populations from Southeastern China were clustered into a"branche",including the individuals from Anhui,Guangxi,Guangdong,Guizhou,Zhejiang,Hunan,Sichuan,Fujian);the populations from Southwestern Yunnan were gathered together and the populations from Tibet were always together.Possibly,their phylogenetic status might close to the Indian species O.cuvera.However,we need more specimens from these areas to clarify their relationship in the future.(4)Species delimitation by ABGD,GMYC and PTP is consistent with phylogenetic analysis.The branch of Southeast China(including O.sinensis,O.fallaciosa and transition form individuals between them)is defined as a same species with regard to the small genetic distance(0.001-0.027)among different geographical populations.As a result,the topology and the genetic distance both supported that O.sinensis,O.fallaciosa and their transition form individuals should belong to a same species with different color pattern on the elytra.The complete mitochondrial genome of O.fallaciosa is obtained for the first time using the NGS technology.The data have been submitted to the GenBank.The characters of this mitogenome processed the typical characteristics of mitochondrial structure in insecta.The complete mitogenome of O.fallaciosa was a closed circle with two strands.It was composed of 13 PCGs(cox 1-3,ND1-6,atp6,atp8,ND4L,and Cytb),22 tRNA genes,2 rRNA genes[rrnS(12S)and rrnL(16S)]and one control region.The starting codons of PCGs are all ATN except coxl is ACC.The phylogenetic tree of 12 protein coding genes showed that Odontolabis fallaciosa and Aegus angustus share a common ancestor.