The Research Of Morphology And DNA Barcoding From Some Species Of Onthophagus

Onthophagus Latreille belongs to Coleoptera, Scarabaeoidea, Scarabaeidae,Scarabaeinae. More than2300species have been known all over the world. Although themorphological characteristics, habits, and phylogeny of Onthophagus were studied a lotpreviously, the reseraches on the morphology, including the sexual dimorphism and maleaedeagus features of the species of Onthophagus from China are very limitedly. SpeciallyDNA barcoding of the classification of the species from the genus Onthophagus in Chinawere few reported.In this paper, some samples of Onthophagus from Liaoning, Shandong, InnerMongolia, Hebei, Henan and Gansu provinces were collected by handing and pitfalltrapping and were identified based on the morphological characters. The externalmorphology, sexual dimorphism, male aedeagus of these samples were researched byobtaining their Photographes and comparing the morphological features. Themitochondrial COⅠ sequences of the species of Onthophagus (14species63samples)were acquired by the PCR amplification technology and21species (24samples) COⅠsequences available from GenBank database were downloaded. The nucleotidecomposition, quantity and distribution of variable sites, genetic distance of intra-speciesand inter-species, haplotype diversity, and nucleotide diversity were analyzed with theMega5.0, DNAsp5.0software. According to the distance NJ tree was established and therelationships between intra-species and inter-species were explored.The results on the morphology of the species of the genus Onthophagus show that themorphological characters among the major species from Onthophagus are distinct and thesexual dimorphism exists widely in species Onthophagus. Features of the sexualdimorphism exhibits mainly the differences of shapes on the head, pronotum and protibiabetween male and female individuals. The shape of male external genital organ is thedifferent among species and is more steady than other rmorphological characters, thereforeit is the reliable identification character. The results of DNA barcoding research revealed that the nucleotide composition of all the sequences was AT-rich, with71.7%A+T andexhibited the bias mitochondrial bases of insect. The hapotype diversity (Hd) was0.983±0.000001and35species87individuals shared65hapotypes, showing that there aresufficient haplotype and the genetic differentiation in the Onthophagus. The analysis onvaribale site distribution revealed that there are45and47varibal sites nearby311bp and661bp on50bp sliding window and there are46and47varibal sites nearby286bp and661bp on75bp sliding window, revealing there was the same high varibale sitedistribution regions on two sliding windows. Genetic distances showed the averageintra-specific divergence was0.88%and the average inter-specific divergence was12.25%.The genetic distance in inter-species was13.9times of that in intra-species and wasconsistent to the genetic distance threshold value between the intra-specific inter-species.Also there were the overlap region of the genetic distances between the intra-specific andthe inter-species because the genetic differentiation in Onthophagus gibbulus populationoccured and the genetic distances of this species was more distinct than that few twospecies. NJ tree demonstrated that all species, including female and male individuals, wererespectively gathered under the branch of the same species with strong support (bootstrapvalue>99%), and then clustered together with other species.The species identification of Onthophagus by DNA barcoding were consistent withthe classfication based on morphology. DNA barcoding was proved as an effective methodfor identifying the species of the genus Onthophagus.