Complete mitochondrial genome of the two-spotted stag beetle,Metopodontus blanchardi(Coleoptera: Lucanidae)

The Phylogenetic Relationship of Lamiinae (Coleoptera: Cerambycidae) Using Mitochondrial Genomes

Lamiinae is the largest subfamily of the Cerambycidae (longhorn beetles), with approximately 21,863 described species. Previous phylogenetic studies of Lamiinae showed that this subfamily was monophyletic, but the relationship between the tribes of Lamiinae is still controversial. Partial molecular data and species morphological characteristics are not sufficient to resolve species phylogenetic studies perfectly. At the same time, the full mitochondrial genome contains more comprehensive genetic data. Benefiting from the development of next-generation sequencing (NGS), mitochondrial genomes can be easily acquired and used as reliable molecular markers to investigate phylogenetic relationships within Cerambycidae. Using NGS technology, we obtained 11 mitochondrial genome sequences of Lamiinae species. Based on this newly generated mitochondrial genome dataset matrix, we reconstructed the phylogeny of Lamiinae. The Bayesian Inference and Maximum Likelihood analyses strongly support the monophyly of four tribes (Lamiini, Batocerini, Mesosini, and Saperdini), whereas the tribe Acanthocinini was identified as paraphyletic. Other mitochondrial structural features were also observed: the start codon in the nad1 gene of all 11 mitochondrial genomes is TTG; 17-22 bp intergenic spacers (IGS) with a 'TACTA' motif were found between trnS2 and nad1. Moreover, two long IGS were found in Mesosa myops and Batocera sp. Tandem repeats were found in the IGS of Batocera sp.

Phylogenetic Implication of Large Intergenic Spacers: Insights from a Mitogenomic Comparison of Prosopocoilus Stag Beetles (Coleoptera: Lucanidae)

Simple Summary

Insect mitochondrial genomes (mitogenomes) show high diversity in some lineages. In the mitogenome of some Coleoptera species, a large intergenic spacer (IGS) has been identified. However, very little is known about mitogenomes of lucanid beetles. In this work, to provide further insight into the phylogenic relationships among species in lucanid beetles (genus Prosopocoilus), two Prosopocoilus species (Prosopocoilus castaneus and Prosopocoilus laterotarsus) were newly sequenced and comparatively analyzed. Significantly, the two newly sequenced Prosopocoilus species contained a large IGS located between trnI and trnQ. Our phylogenomic analyses showed that P. castaneus and P. laterotarsus were clustered in a clade with typical Prosopocoilus species (Prosopocoilus confucius, Prosopocoilus blanchardi, and Prosopocoilusastacoides). These results provide valuable data for the future study of the phylogenetic relationships in this genus.

Abstract

To explore the characteristics of mitogenomes and discuss the phylogenetic relationships within the genus Prosopocoilus, the mitogenomes of two species (P. castaneus and P. laterotarsus) were newly sequenced and comparatively analyzed. The arrangement of the mitogenome in these two lucanid beetles was the same as that in the inferred ancestral insect, and the nucleotide composition was highly biased towards A + T as in other lucanids. The evolutionary rates of 13 protein-coding genes (PCGs) suggested that their evolution was based on purifying selection. Notably, we found evidence of the presence of a large IGS between trnI and trnQ genes, whose length varied from 375 bp (in P. castaneus) to 158 bp (in P. laterotarsus). Within the large IGS region, a short sequence (TAAAA) was found to be unique among these two species, providing insights into phylogenomic reconstruction. Phylogenetic analyses were performed using the maximum likelihood (IQ-TREE) and Bayesian (PhyloBayes) methods based on 13 protein-coding genes (PCGs) in nucleotides and amino acids (AA) from published mitogenomes (n = 29). The genus Prosopocoilus was found to constitute a distinct clade with high nodal support. Overall, our findings suggested that analysis of the characteristics of the large IGS (presence or absence, size, and location) in mitogenomes of the genus Prosopocoilus may be informative for the phylogenetic and taxonomic analyses and for evaluation of the genus Prosopocoilus, despite the dense sampling materials needed.

Comprehensive Analyses of the Complete Mitochondrial Genome of Figulus binodulus (Coleoptera: Lucanidae)

Figulus binodulus Waterhouse is a small stag beetle distributed in East Asia. We determined the first mitochondrial genome of F. binodulus of which is 16,261-bp long including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNAs, and a single large noncoding region of 1,717 bp. Gene order of F. binodulus is identical to the ancestral insect mitochondrial gene order as in most other stag beetle species. All of 22 tRNAs could be shaped into typical clover-leaf structure except trnSer1. Comparative analyses of 21 Lucanidae mitochondrial genomes was conducted in aspect of their length and AT-GC ratio. Nucleotide diversities analyses provide that cox1 and cox2 in Lucanidae are less diverse than those of Scarabaeoidea. Fifty simple sequence repeats (SSRs) were identified on F. binodulus mitochondrial genome. Comparative analysis of SSRs among five mitochondrial genomes displayed similar trend along with SSR types. Figulus binodulus was sister to all other available family Lucanidae species in the phylogenetic tree.

The complete mitochondrial genome of stag beetle Lucanus cervus (Coleoptera: Lucanidae) and phylogenetic analysis

Background

The stag beetle Lucanus cervus (Coleoptera: Lucanidae) is widely distributed in Europe. Habitat loss and fragmentation has led to significant reductions in numbers of this species. In this study, we sequenced the complete mitochondrial genome of L. cervus and reconstructed phylogenetic relationships among Lucanidae using complete mitochondrial genome sequences.

Methods

Raw data sequences were generated by the next generation sequencing using Illumina platform from genomic DNA of L. cervus. The mitochondrial genome was assembled by IDBA and annotated by MITOS. The aligned sequences of mitochondrial genes were partitioned using PartitionFinder 2. Phylogenetic relationships among 19 stag beetle species were constructed using Maximum Likelihood (ML) method implemented in IQ-TREE web server and Bayesian method implemented in PhyloBayes MPI 1.5a. Three scarab beetles were used as outgroups.

Results

The complete mitochondrial genome of L. cervus is 20,109 bp in length, comprising 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNAs and a control region. The A + T content is 69.93% for the majority strand. All protein-coding genes start with the typical ATN initiation codons except for cox1, which uses AAT. Phylogenetic analyses based on ML and Bayesian methods shown consistent topologies among Lucanidae.

Characterisation of the complete mitochondrial genome of Lucanus chengyuani (Coleoptera: Lucanidae)

We sequenced and assembled the complete mitochondrial genome of Lucanus chengyuani, from the Alishan, Chiayi County, Taiwan. The length of the complete mitogenome of L. chengyuani is 16,926 bp and the mitogenome contains 13 protein-coding, 22 tRNA, and 2 rDNA genes. Nucleotide compositions of the whole mitogenome of L. chengyuani are 38.37% for A, 27.96% for T, 23.03% for C, and 10.637% for G. The AT and GC skewness of mitogenome sequence are 0.157 and -0.368, showing the A-skew and C-skew. The reconstructed phylogenetic relationships of 9 Lucanidae species based on 13 mitochondrial protein-coding genes are highly supported. The clade including Neolucanus maximus and Odontolabis cuvera is sister to the rest of the stag beetle clades, which contains L. chengyuani and L. mazama. Mitogenomic data from this study will provide useful information for further studies for the population genetics, speciation, biogeography, and conservation of L. chengyuani in the future.

Two new complete mitochondrial genomes of Dorcus stag beetles (Coleoptera, Lucanidae)

The systematics of Dorcus MacLeay has been a long-standing debate. Mitochondrial genomes were widely used to deeply understand the phylogeny of problematic taxa in virtue of their genetic importance and comprehensiveness. To provide more useful genetic data for resolving the systematic disputation of Dorcus stag beetles. The complete mitochondrial genomes of Dorcus hopei and Dorcus seguyi were obtained using the next generation sequencing. Characteristics of the two genomes are explicated through comparing their genome organization and base composition, protein-coding genes and codon usage, intergenic spacers and non-coding region, transfer and ribosomal RNA genes and control region. Phylogenetic relationships were reconstructed using Maximum likelihood and Bayesian inference analyses based on the concatenated nucleotide sequences of 13 PCGs from 9 stag beetles and 3 scarab beetles. The complete mitogenomes of D. hopei and D. seguyi was 16,026 bp/17,955 bp long, respectively. A tandem repeat with the length of 940 bp was presented in the A+T-rich region in D. hopei. An unexpected non-coding region of 332 bp was located between nad2 and trnW in D. seguyi. The phylogenetic analyses robustly supported that D. hopei formed a branch with the generic type of D. parallelipipedus. Whereas D. seguyi was not covered in the branch of (D. hopei + D. parallelipipedus), but was sister to them. The results indicated that D. hopei should be a good member of Dorcus MacLeay. The taxonomic status of D. seguyi remained to be studied furtherly.

Complete mitochondrial genome of a leaf-mining beetle, Rhadinosa nigrocyanea (Coleoptera: Chrysomelidae) with phylogenetic consideration

The complete circular mitochondrial genome (mitogenome) of Rhadinosa nigrocyanea was 17,965 bp in length, which contained 2 ribosomal RNA genes, 22 transfer RNAs, 13 protein-coding genes (PCGs) and 1 non-coding AT-rich region with the length of 3002 bp. All of the 22 tRNA genes displayed a typical clover-leaf structure, with the exception of tRNA^Ser (TCT). 12 PCGs were initiated by ATN codons, except for ND1 started with TTG. Only six PCGs used the typical stop codon ‘TAA’ and ‘TGA’, while seven PCGs terminated with incomplete stop codons (TA or T). Phylogenetic analysis showed that R. nigrocyanea grouped with Cassidinae species, sister to Clytrinae + Cryptocephalinae.

The mitochondrial genome of the multicolored Asian lady beetle Harmonia axyridis (Pallas) and a phylogenetic analysis of the Polyphaga (Insecta: Coleoptera)

Here, we report the mitochondrial genome sequence of the multicolored Asian lady beetle Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) (GenBank accession No. KR108208). This is the first species with sequenced mitochondrial genome from the genus Harmonia. The current length with partitial A + T-rich region of this mitochondrial genome is 16,387 bp. All the typical genes were sequenced except the trnI and trnQ. As in most other sequenced mitochondrial genomes of Coleoptera, there is no re-arrangement in the sequenced region compared with the pupative ancestral arrangement of insects. All protein-coding genes start with ATN codons. Five, five and three protein-coding genes stop with termination codon TAA, TA and T, respectively. Phylogenetic analysis using Bayesian method based on the first and second codon positions of the protein-coding genes supported that the Scirtidae is a basal lineage of Polyphaga. The Harmonia and the Coccinella form a sister lineage. The monophyly of Staphyliniformia, Scarabaeiformia and Cucujiformia was supported. The Buprestidae was found to be a sister group to the Bostrichiformia.

The first complete mitochondrial genome of stag beetle from China, Prosopocoilus gracilis (Coleoptera, Lucanidae)

The complete mitochondrial genome (mitogenome) of Prosopocoilus gracilis (Coleoptera: Lucanidae) that is endemic to Southern China is determined. The circular genome is 736 bp in length and comprises 13 protein-coding genes, 22 tRNA, 2 rRNA genes and a control region. Gene order is identical to that of the putative ancestral arrangement of insects. The nucleotide composition of heavy strand is A (36.6%), C (22.6%), T (29.5%) and G (11.3%). All protein-coding genes start with a typical ATN codon except for the gene COI that uses AAC as the start codon. tRNA-Ser (AGN) uses the anticodon UCU instead of the commonly used GCU. Both maximum likelihood and Bayesian analyses support the monophyly of Lucanidae and the sister relationship of Nigidionus and the remaining sampled genera. Two species of Prosopocoilus were not recovered as a monophyletic group.

The complete mitochondrial genome of the confused flour beetle Tribolium confusum (Coleoptera: Tenebrionidae)

Flour beetles of the genus Tribolium are economically important as destructive cosmopolitan pests of stored flour, corn, peanuts, and other dried agricultural products. The confused flour beetle Tribolium confusum Jacquelin du Val (1868) is one of the most important pest species of flour beetle. Here we sequenced and characterized the complete mitochondrial genome of T. confusum, the entire sequence is 15,813 bp in size with 72.8% AT content. It consists of 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA), 2 ribosomal RNA (rRNA) genes and one major non-coding AT-rich region. The mitogenome of T. confusum exhibits a gene arrangement and content identical to the most common type in insects. All PCGs are start with a typical ATN initiation codon, except for the cox1, which use AAC as its start codon instead of ATN. Ten genes use standard complete termination codon (six TAA, three TAG), whereas the cox2, cox3, nad4 and nad5 genes end with single T. Except for trnS1 ((AGN)), all tRNA genes display typical secondary cloverleaf structures as those of other insects. The sizes of the large and small ribosomal RNA genes are 1277 and 773 bp, respectively. The AT content of the AT-rich region is 79.5%. The 5 bp conserved motif TACTA was found in the intergenic region between trnS2 ((UCN)) and nad1.

The complete mitochondrial genome of the red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae)

The complete mitochondrial genome (mitogenome) of Tribolium castaneum (Coleoptera: Tenebrionidae) was determined to be 15,883 bp (GenBank accession No. KM009121), which contains 22 tRNA genes, 13 protein-coding genes (PCGs), 2 rRNA genes and a major non-coding A + T-rich region. It has the typical gene organization and order of mitogenomes from ancestral insects. The nucleotide composition was also biased toward A + T nucleotides (71.72%) and the AT skew of this mitogenome was slightly positive. All of the 22 tRNA genes displayed a typical clover-leaf structure, with the exception of trnS1 (AGN). Thirteen PCGs were initiated by ATN codons, except for cytochrome c oxidase subunit 1 (cox1) gene which was initiated by AAT. Eight of the 13 PCGs harbor the incomplete termination codon by T or TA. The A + T-rich region of the mitogenome was 1237 bp in length and the A + T content was 82.30%.