The mitochondrial genomes of three skippers: Insights into the evolution of the family Hesperiidae (Lepidoptera)

Structural Characteristics and Phylogenetic Analysis of the Mitochondrial Genomes of Four Krisna Species (Hemiptera: Cicadellidae: Iassinae)

Krisna species are insects that have piercing-sucking mouthparts and belong to the Krisnini tribe in the Iassinae subfamily of leafhoppers in the Cicadellidae family. In this study, we sequenced and compared the mitochondrial genomes (mitogenomes) of four Krisna species. The results showed that all four mitogenomes were composed of cyclic double-stranded molecules and contained 13 protein-coding genes (PCGs) and 22 and 2 genes coding for tRNAs and rRNAs, respectively. Those mitogenomes exhibited similar base composition, gene size, and codon usage patterns for the protein-coding genes. The analysis of the nonsynonymous substitution rate (Ka)/synonymous substitution rate (Ks) showed that evolution occurred the fastest in ND4 and the slowest in COI. 13 PCGs that underwent purification selection were suitable for studying phylogenetic relationships within Krisna. ND2, ND6, and ATP6 had highly variable nucleotide diversity, whereas COI and ND1 exhibited the lowest diversity. Genes or gene regions with high nucleotide diversity can provide potential marker candidates for population genetics and species delimitation in Krisna. Analyses of parity and neutral plots showed that both natural selection and mutation pressure affected the codon usage bias. In the phylogenetic analysis, all subfamilies were restored to a monophyletic group; the Krisnini tribe is monophyletic, and the Krisna genus is paraphyletic. Our study provides novel insights into the significance of the background nucleotide composition and codon usage patterns in the CDSs of the 13 mitochondrial PCGs of the Krisna genome, which could enable the identification of a different gene organization and may be used for accurate phylogenetic analysis of Krisna species.

Phylogenetic and Evolutionary Comparison of Mitogenomes Reveal Adaptive Radiation of Lampriform Fishes

Lampriform fishes (Lampriformes), which primarily inhabit deep-sea environments, are large marine fishes varying from the whole-body endothermic opah to the world's longest bony fish-giant oarfish, with species morphologies varying from long and thin to deep and compressed, making them an ideal model for studying the adaptive radiation of teleost fishes. Moreover, this group is important from a phylogenetic perspective owing to their ancient origins among teleosts. However, knowledge about the group is limited, which is, at least partially, due to the dearth of recorded molecular data. This study is the first to analyze the mitochondrial genomes of three lampriform species (Lampris incognitus, Trachipterus ishikawae, and Regalecus russelii) and infer a time-calibrated phylogeny, including 68 species among 29 orders. Our phylomitogenomic analyses support the classification of Lampriformes as monophyletic and sister to Acanthopterygii; hence, addressing the longstanding controversy regarding the phylogenetic status of Lampriformes among teleosts. Comparative mitogenomic analyses indicate that tRNA losses existed in at least five Lampriformes species, which may reveal the mitogenomic structure variation associated with adaptive radiation. However, codon usage in Lampriformes did not change significantly, and it is hypothesized that the nucleus transported the corresponding tRNA, which led to function substitutions. The positive selection analysis revealed that atp8 and cox3 were positively selected in opah, which might have co-evolved with the endothermic trait. This study provides important insights into the systematic taxonomy and adaptive evolution studies of Lampriformes species.

The mitochondrial genomes of the Geometroidea (Lepidoptera) and their phylogenetic implications

The Geometroidea is a large superfamily of Lepidoptera in species composition and contains numerous economically important pest species that cause great loss in crop and forest production. However, understanding of mitogenomes remains limited due to relatively fewer mitogenomes previously reported for this megadiverse group. Here, we sequenced and annotated nine mitogenomes for Geometridae and further analyzed the mitogenomic evolution and phylogeny of the whole superfamily. All nine mitogenomes contained 37 mitochondrial genes typical in insects, and gene organization was conserved except for Somatina indicataria. In S. indicataria, the positions of two tRNAs were rearranged. The trnR was located before trnA instead of after trnA typical in Lepidoptera, whereas the trnE was detected rarely on the minority strand (N-strand). This trnR-trnA-trnN-trnS1-trnE-trnF newly recognized in S. indicataria represents the first gene rearrangement reported for Geometroidea and is also unique in Lepidoptera. Besides, nucleotide composition analyses showed little heterogeneity among the four geometrid subfamilies involved herein, and overall, nad6 and atp8 have higher nucleotide diversity and Ka/Ks rate in Geometridae. In addition, the taxonomic assignments of the nine species, historically defined by morphological studies, were confirmed by various phylogenetic analyses based on the hitherto most extensive mitogenomic sampling in Geometroidea.

The first complete mitochondrial genome of Matsucoccidae (Hemiptera, Coccoidea) and implications for its phylogenetic position

The mitochondrial genome (mitogenome) has been extensively used to better understand the phylogenetic relationships within the hemipteran suborder Sternorrhyncha, but sequenced mitogenomes remain unavailable for the entire family Matsucoccidae to date. To address this, here we sequenced the complete mitogenome of Matsucoccusmatsumurae; the first for this family. The mitogenome is 15,360 bp in size and comprises the typical set of 37 mitochondrial genes and a large non-coding region (AT-rich region). Gene order, nucleotide composition and codon usage of protein-coding genes (PCGs) of M.matsumurae differ considerably from those of the other two sequenced Coccidae species. All PCGs were initiated by the ATN start codons and ended with the TAA/G or single T-- stop codons. Nine transfer RNA genes could be folded into typical clover-leaf secondary structures. The length and AT content of the ribosomal RNA genes are highly conserved in the Coccoidea mitogenomes. In contrast, the AT-rich control region is highly variable in size and in the number of tandem repeats. The sliding window analysis showed that the cox1 gene is the most conserved amongst the 13 PCGs, while the ratios of non-synonymous to synonymous substitution rates indicated that the evolution of this mitogenome has been dominated by positive selection. Phylogenetic analyses, based on nucleotide sequence data of 37 mitochondrial genes and amino acid sequence data of 13 PCGs using Bayesian Inference and Maximum Likelihood methods, showed that Matsucoccidae diverged before the Coccidae.

Description and complete mitochondrial genome of Atkinsoniella zizhongi sp. nov. (Hemiptera: Cicadellidae: Cicadellinae) from China and its phylogenetic implications

A new species, Atkinsoniella zizhongi sp. nov. of the subfamily Cicadellinae, was described and illustrated from China. The new species is similar to A. nigrominiatula (Jacobi, 1944), A. limba Kuoh, 1991, A. dormana Li, 1992, A. peaka Yang, Meng et Li, 2017, and A. divaricata Yang, Meng et Li, 2017. But the characteristics of aedeagus and pygofer process can be used to distinguish them easily. The complete mitochondrial genome of the paratype was sequenced and assembled. The mitogenome of A. zizhongi sp. nov. was 16,483 bp in length, with an A+T content of 75.9%, containing 37 typical genes and a control region (CR). The gene order was consistent with the inferred insect ancestral mitochondrial genome. All of the PCGs were determined to have the typical stop codon TAA or TAG, while COX2 and ND5 ended with incomplete termination codons T and TA, respectively. In addition, phylogenetic trees were reconstructed based on PCGs and rRNAs using both the maximum likelihood (ML) and Bayesian inference (BI) methods. The results showed that the intergeneric and interspecific relationships within the subfamily Cicadellinae were completely consistent in all of the phylogenetic trees, except that the different interspecific relationships within the genus Bothrogonia were detected in the ML analysis based on the amino acid sequences. This study enriches the species diversity of Cicadellinae and further promotes research on its phylogeny.

Comparative Mitogenomics of Flesh Flies: Implications for Phylogeny

Flesh flies (Diptera: Sarcophagidae) represent a rapid radiation belonging to the Calyptratae. With more than 3000 known species, they are extraordinarily diverse in terms of their breeding habits and are therefore of particular importance in human and veterinary medicine, forensics, and ecology. To better comprehend the phylogenetic relationships and evolutionary characteristics of the Sarcophagidae, we sequenced the complete mitochondrial genomes of five species of flesh flies and performed mitogenomic comparisons amongst the three subfamilies. The mitochondrial genomes match the hypothetical condition of the insect ancestor in terms of gene content and gene arrangement. The evolutionary rates of the subfamilies of Sarcophagidae differ significantly, with Miltogramminae exhibiting a higher rate than the other two subfamilies. The monophyly of the Sarcophagidae and each subfamily is strongly supported by phylogenetic analysis, with the subfamily-level relationship inferred as (Sarcophaginae, (Miltogramminae, Paramacronychiinae)). This study suggests that phylogenetic analysis based on mitochondrial genomes may not be appropriate for rapidly evolving groups such as Miltogramminae and that the third-codon positions could play a considerable role in reconstructing the phylogeny of Sarcophagidae. The protein-coding genes ND2 and ND6 have the potential to be employed as DNA markers for species identification and delimitation in flesh flies.

Mitogenomes of Nine Asian Skipper Genera and Their Phylogenetic Position (Lepidoptera: Hesperiidae: Pyrginae)

In this study, complete mitochondrial genomes of nine species representing three tribes in the subfamily Pyrginae sensu lato were newly sequenced. The mitogenomes are closed double-stranded circular molecules, with the length ranging from 15,232 bp to 15,559 bp, which all encode 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a control region. The orientation and gene order of these nine mitogenomes are identical to the inferred ancestral arrangement of insects. All PCGs exhibit the typical start codon ATN except for cox1 (using CGA) and cox2 (using TTG) in Mooreana trichoneura. Most of the PCGs terminate with a TAA stop codon, while cox1, cox2, nad4, and nad5 end with the incomplete codon single T. For the different datasets, we found that the one comprising all 37 genes of the mitogenome produced the highest nodal support, indicating that the inclusion of RNAs improves the phylogenetic signal. This study re-confirmed the status of Capila, Pseudocoladenia, and Sarangesa; namely, Capila belongs to the tribe Tagiadini, and Pseudocoladenia and Sarangesa to the tribe Celaenorrhini. Diagnostic characters distinguishing the two tribes, the length of the forewing cell and labial palpi, are no longer significant. Two populations of Pseudocoladenia dan fabia from China and Myanmar and P. dan dhyana from Thailand are confirmed as conspecific.

Complete mitochondrial genome sequence of Abraximorpha davidii (Lepidoptera: Hesperiidae: Tagiadinae)

Taxonomic status and phylogenetic position of some skippers within Hesperiidae remains a controversial issue, here, we sequenced and analyzed the complete mitochondrial genome (mitogenome) of Abraximorpha davidii, one of species in Hesperiidae. This mitogenome is 15,469 bp long and encodes 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA unit genes (rRNAs). The overall base composition of the mitogenome is A 40.2%, T 41.4%, C 11.2%, and G 7.2%, with a high A + T content of 81.6%. Except for cox1 starting with CGA, all other PCGs start with the standard ATN codons (seven ATG and five ATT). Most of the PCGs terminate with the stop codon TAA, whereas cox1, cox2, nad5, and nad4 end with the incomplete codon T−. Phylogenetic analysis showed that A. davidii is closely related to Daimio tethys and Tagiades vajuna, then this clade clusters Ctenoptilum vasava and Celaenorrhinus maculosa.

The Complete Mitochondrial Genomes of Four Species in the Subfamily Limenitidinae (Lepidoptera, Nymphalidae) and a Phylogenetic Analysis

Simple Summary

As it is currently delineated, the subfamily Limenitidinae (Lepidoptera: Nymphalidae) is comprised of 50 genera with approximately 1100 species. The classification of this subfamily has always been unstable. There are tribes and genera whose status is doubtful. Their phylogenetic relationships are far from being clarified and the monophyly of some of them is under question. To provide further insight into the relationships among included tribes, four newly-completed mitochondrial genomes of Limenitidinae (Neptis thisbe, Athyma zeroca, and Aldania raddei) have been sequenced and analyzed. Results indicate that the gene orientation and arrangement are similar to typical mitogenomes in Lepidoptera. The inferred phylogenetic analysis shows that tribe levels are well-supported monophyletic groups. Taken together, this work will provide a well-resolved framework for future study of this subfamily.

Abstract

The complete mitogenomes of four species, Neptis thisbe, Neptis obscurior, Athyma zeroca, and Aldania raddei, were sequenced with sizes ranging from 15,172 bp (N. obscurior) to 16,348 bp (Al. raddei). All four mitogenomes display similar nucleotide content and codon usage of protein-coding genes (PCGs). Typical cloverleaf secondary structures are identified in 21 tRNA genes, while trnS1 (AGN) lacks the dihydrouridine (DHC) arm. The gene orientation and arrangement of the four mitogenomes are similar to that of other typical mitogenomes of Lepidoptera. The Ka/Ks ratio of 13 PCGs among 58 Limenitidinae species reveals that cox1 had the slowest evolutionary rate, while atp8 and nad6 exhibited a higher evolutionary rate. The phylogenetic analysis reveals that tribe-levels are well-supported monophyletic groups. Additionally, Maximum Likelihood analysis recovered the relationship (Parthenini + ((Chalingini + (Cymothoini + Neptini)) + (Adoliadini + Limenitidini))). However, a Bayesian analysis based on the same dataset recovered the relationship (Parthenini + (Adoliadini + ((Cymothoini + Neptini) + (Chalingini + Limenitidini)))). These results will offer valuable data for the future study of the phylogenetic relationships for Limenitidinae.

The mitochondrial genomes of Tortricidae: nucleotide composition, gene variation and phylogenetic performance

BACKGROUND

Mitochondrial genomes (mitogenomes) have greatly improved our understanding of the backbone phylogeny of Lepidoptera, but few studies on comparative mitogenomics below the family level have been conducted. Here, we generated 13 mitogenomes of eight tortricid species, reannotated 27 previously reported mitogenomes, and systematically performed a comparative analysis of nucleotide composition, gene variation and phylogenetic performance.

RESULTS

The lengths of completely sequenced mitogenomes ranged from 15,440 bp to 15,778 bp, and the gene content and organization were conserved in Tortricidae and typical for Lepidoptera. Analyses of AT-skew and GC-skew, the effective number of codons and the codon bias index all show a base bias in Tortricidae, with little heterogeneity among the major tortricid groups. Variations in the divergence rates among 13 protein-coding genes of the same tortricid subgroup and of the same PCG among tortricid subgroups were detected. The secondary structures of 22 transfer RNA genes and two ribosomal RNA genes were predicted and comparatively illustrated, showing evolutionary heterogeneity among different RNAs or different regions of the same RNA. The phylogenetic uncertainty of Enarmoniini in Tortricidae was confirmed. The synonymy of Bactrini and Olethreutini was confirmed for the first time, with the representative Bactrini consistently nesting in the Olethreutini clade. Nad6 exhibits the highest phylogenetic informativeness from the root to the tip of the resulting tree, and the combination of the third coding positions of 13 protein-coding genes shows extremely high phylogenetic informativeness.

CONCLUSIONS

This study presents 13 mitogenomes of eight tortricid species and represents the first detailed comparative mitogenomics study of Tortricidae. The results further our understanding of the evolutionary architectures of tortricid mitogenomes and provide a basis for future studies of population genetics and phylogenetic investigations in this group.

Comparative Mitogenomic Analysis of Five Awl Skippers (Lepidoptera: Hesperiidae: Coeliadinae) and Their Phylogenetic Implications

Simple Summary

The subfamily Coeliadinae (Lepidoptera: Hesperiidae) is a unique group of over 70 species in the butterfly family, and its mitochondrial genome data still needs to be supplemented. This study sequenced and analyzed five additional complete mitochondrial genomes of the Coeliadinae species (Hasora schoenherr, Burara miracula, B. oedipodea, B. harisa, and Badamia exclamationis) and compared them in detail with those of the other known skipper mitogenomes. All five of these mitogenomes have the typical lepidopteran mitogenome characteristics of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a non-coding region. Our results indicate that their structure, nucleotide composition, codon usage, secondary structure of tRNAs, and so on, are highly conserved. Expanded sampling and gene data from the GenBank, phylogenetic analyses using maximum likelihood, and Bayesian inference methods indicate that Coeliadinae is monophyletic. These results contribute toward refining the phylogeny.

Abstract

To determine the significance of mitochondrial genome characteristics in revealing phylogenetic relationships and to shed light on the molecular evolution of the Coeliadinae species, the complete mitochondrial genomes (mitogenomes) of five Coeliadinae species were newly sequenced and analyzed, including Hasora schoenherr, Burara miracula, B. oedipodea, B. harisa, and Badamia exclamationis. The results show that all five mitogenomes are double-strand circular DNA molecules, with lengths of 15,340 bp, 15,295 bp, 15,304 bp, 15,295 bp, and 15,289 bp, respectively, and contain the typical 37 genes and a control region. Most protein-coding genes (PCGs) begin with ATN, with 3 types of stop codons including TAA, TAG, and an incomplete codon T-; most of the genes terminate with TAA. All of the transfer RNA genes (tRNAs) present the typical cloverleaf secondary structure except for the trnS1. Several conserved structural elements are found in the AT-rich region. Phylogenetic analyses based on three datasets (PCGs, PRT, and 12PRT) and using maximum likelihood (ML) and Bayesian inference (BI) methods show strong support for the monophyly of Coeliadinae, and the relationships of the five species are (B. exclamationis + ((B. harisa + (B. oedipodea + B. miracula)) + H. schoenherr)).

Characterization and Phylogenetic Analysis of the Mitochondrial Genome Sequence of Nisia fuliginosa (Hemiptera: Fulgoroidea: Meenoplidae)

We explored characterization of the mitochondrial genome (mitogenome or mtGenome) and phylogenetic analysis between 32 Fulgoroid species by sequencing and analyzing the mitogenome of Nisia fuliginosa Yang and Hu, 1985 (Hemiptera: Fulgoroidea: Meenoplidae), thereby making it the first determined mitogenome from the family Meenoplidae. The mitogenome was found to be 15,754 bp in length and contained 13 protein-coding genes (PCGs), 22 tRNA genes, two ribosomal RNA genes (rRNAs), and a control region. All PCGs started with typical ATN codons, except for nad1, which used GTG as the start codon. Canonical TAA termination codons were found in 10 PCGs and the remaining three genes (cox2, nad6, and nad1) had incomplete stop codons T. All tRNAs could fold into typical cloverleaf secondary structures, with the exception of trnC, trnV, and trnS1. Additionally, we compared the AT and GC skews of 13 PCGs of 32 Fulgoroidea mitogenomes, on the L-strand, the AT and GC skews were negative and positive, respectively. However, on the H-strand, the AT skew could be positive or negative and the GC skew was always negative. Phylogenetic results showed that the eight families of Fulgoroidea were divided into two large groups. Delphacidae formed a monophyletic group sister to a clade comprising Meenoplidae and other six families (Fulgoridae, Ricaniidae, Flatidae, Issidae, Caliscelidae, and Achilidae). Meenoplidae was located near the clade of Delphacidae, and Fulgoridae was located near the clade of Meenoplidae. Furthermore, Caliscelidae, Issidae, Ricaniidae, and Flatidae are closely related and they collectively formed a sister group to Achilidae.

Complete mitochondrial genomes of three skippers in the tribe Aeromachini (Lepidoptera: Hesperiidae: Hesperiinae) and their phylogenetic implications

The mitochondrial genome is now widely used in the study of phylogenetics and molecular evolution due to its maternal inheritance, fast evolutionary rate, and highly conserved gene content. To explore the phylogenetic relationships of the tribe Aeromachini within the subfamily Hesperiinae at the mitochondrial genomic level, we sequenced and annotated the complete mitogenomes of 3 skippers: Ampittia virgata, Halpe nephele, and Onryza maga (new mitogenomes for 2 genera) with a total length of 15,333 bp, 15,291 bp, and 15,381 bp, respectively. The mitogenomes all contain 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs), and a noncoding A + T-rich region and are consistent with other lepidopterans in gene order and type. In addition, we reconstructed the phylogenetic trees of Hesperiinae using maximum likelihood (ML) and Bayesian inference (BI) methods based on mitogenomic data. Results show that the tribe Aeromachini in this study robustly constitute a monophyletic group in the subfamily Hesperiinae, with the relationships Coeliadinae + (Euschemoninae + (Pyrginae + ((Eudaminae + Tagiadinae) + (Heteropterinae + ((Trapezitinae + Barcinae) + Hesperiinae))))). Moreover, our study supports the view that Apostictopterus fuliginosus and Barca bicolor should be placed out of the subfamily Hesperiinae.

The complete mitochondrial genomes of two erythroneurine leafhoppers (Hemiptera, Cicadellidae, Typhlocybinae, Erythroneurini) with assessment of the phylogenetic status and relationships of tribes of Typhlocybinae

The number and classification of tribes in the leafhopper subfamily Typhlocybinae are not yet fully clear, and molecular data has recently been used to help resolve the problem. In this study, the mitochondrial genomes of Mitjaeviashibingensis Chen, Song & Webb, 2020 and M.dworakowskae Chen, Song & Webb, 2020 of the tribe Erythroneurini (Cicadellidae, Typhlocybinae) were sequenced. Most protein-coding genes (PCGs) start with ATN and end with TAA or TAG, and the AT content of these three codons were found differ from previous results that show that the first codon has the highest incidence. Two rRNA genes are highly conserved, and the AT content in 16S is higher than that of 12S. The nucleotide diversity and genetic distance among 13 PCGs of the four tribes from Typhlocybinae show that Empoascini nucleotide diversity is significantly less than in the other three tribes, and have the largest distance from the others, while Typhlocybini and Zyginellini have the smallest distance, indicating that the relationship between the two is the closest. The nad2, nad4, nad4L, and nad5 genes have greater nucleotide diversity, showing potential for use as the main markers for species identification. The phylogenetic analysis yielded a well-supported topology with most branches receiving maximum support and a few branches pertaining to relationships within Zyginellini and Typhlocybini receiving lower support. The species of these two tribes are intertwined, and it was impossible to resolve them into separate branches. In addition, the tribes Empoascini and Erythroneurini were recovered as monophyletic, and Alebrini was placed at the base of the tree as the most primitive. These results are broadly in line with other molecular phylogenetical studies which differ from traditional morphological classification.

Structural features and phylogenetic implications of Cicadellidae subfamily and two new mitogenomes leafhoppers

Complete mitochondrial genome sequences facilitate species identification and analyses of phylogenetic relationships. However, the available data are limited to the diverse and widespread insect family Cicadellidae. This study analyzes and summarizes the complete mitochondrial genome structure characteristics of 11 leafhopper subfamilies and two newly sequenced Typhlocybinae species, Empoascanara wengangensis and E. gracilis. Moreover, using 13PCGs and rRNA data to analyze the nucleotide diversity, evolution rate, and the phylogenetic relationship between the subfamilies of 56 species, verifying the taxonomic status analysis of E. wengangensis and E. gracilis. The analysis results show that the genome structures of the subfamilies and the newly sequenced two species are very similar, and the size of the CR region is significantly related to the repeat unit. However, in the entire AT-skews and CG-skews, the AT-skews of other subfamilies are all positive, and CG-skews are negative, while Empoascini of Typhlocybinae and Ledrinae are the opposite. Furthermore, among 13PCGs, the AT-skews of 13 species are all negative while CG-skews are positive, which from Empoascini in Typhlocybinae, Idiocerinae, Cicadellinae, Ledrinae, and Evacanthinae. Phylogenetic analysis shows that ML and PB analysis produce almost consistent topologies between different data sets and models, and some relationships are highly supported and remain unchanged. Mileewinae is a monophyletic group and is a sister group with Typhlocybinae, and the sister group of Evacanthinae is Ledrinae + Cicadellinae. Phylogenetic analysis grouped the two newly sequenced species with other species of Typhlocybinae, which was separated from other subfamilies, and all Erythroneurini insects gathered together. However, E. gracilis grouped into a single group, not grouped with species of the same genus (Empoascanara). This result does not match the traditional classification, and other nuclear genes or transcriptome genes may be needed to verify the result. Nucleotide diversity analysis shows that nad4 and nad5 may be evaluated as potential DNA markers defining the Cicadellidae insect species.

Unique Duplication of trnN in Odontoptilum angulatum (Lepidoptera: Pyrginae) and Phylogeny within Hesperiidae

To explore the variation and relationship between gene rearrangement and phylogenetic effectiveness of mitogenomes among lineages of the diversification of the tribe Tagiadini in the subfamily Pyrginae, we sequenced the complete mitogenome of Odontoptilum angulatum. The genome is 15,361 bp with the typical 37 genes, a large AT-rich region and an additional trnN (trnN2), which is completely identical to trnN (sequence similarity: 100%). The gene order differs from the typical Lepidoptera-specific arrangement and is unique to Hesperiidae. The presence of a "pseudo-trnS1" in the non-coding region between trnN1 and trnN2 supports the hypothesis that the presence of an extra trnN can be explained by the tandem duplication-random loss (TDRL) model. Regarding the phylogenetic analyses, we found that the dataset comprising all 37 genes produced the highest node support, as well as a monophyly of Pyrginae, indicating that the inclusion of RNAs improves the phylogenetic signal. Relationships among the subfamilies in Hesperiidae were also in general agreement with the results of previous studies. The monophyly of Tagiadini is strongly supported. Our study provides a new orientation for application of compositional and mutational biases of mitogenomes in phylogenetic analysis of Tagiadini and even all Hesperiidae based on larger taxon sampling in the future.

Comparative Mitogenomic Analysis of Heptageniid Mayflies (Insecta: Ephemeroptera): Conserved Intergenic Spacer and tRNA Gene Duplication

Large intergenic spacers and tRNA gene duplications have been reported in several insect groups, although little is known about mitogenomes of mayflies. Here, we determined complete mitogenomes of ten heptageniid species and systemically analyzed their mitogenomic features. Both a conserved intergenic spacer (IGS) and trnM duplication were detected in those mitogenomes. The IGS, which was observed in heptageniids, could be further folded into a stable stem-loop structure. The tRNA gene duplication was found in almost all analyzed mitogenomes, and a unique gene block trnI-trnM-trnQ-trnM-ND2 was also discovered. Our analysis demonstrates that the heptageniid gene arrangement pattern can be explained by the tandem duplication-random loss (TDRL) model. Phylogenetic analyses using both Bayesian inference (BI) and maximum likelihood (ML) methods based on the nucleotide and amino acid sequence data recovered the genus Epeorus as monophyletic with strong support. Our results provide a better understanding of mitogenomic evolution in Heptageniidae, as well as novel molecular markers for species identification of mayflies.

Characterization of the Complete Mitochondrial Genomes of Two Species with Preliminary Investigation on Phylogenetic Status of Zyginellini (Hemiptera: Cicadellidae: Typhlocybinae)

To explore the characteristics of mitogenomes and reveal phylogenetic relationships of the tribes of Zyginellini and Typhlocybini in Typhlocybinae, mitogenomes of two species of the Zyginellini, Parazyginella tiani and Limassolla sp., were sequenced. Mitogenomes of both species contain 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and a large non-coding region (A + T-rich region). These characteristics are similar to other Membracoidea mitogenomes. All PCGs initiate with the standard start codon of ATN and terminate with the complete stop codon of TAA/G or with an incomplete T codon. All tRNAs have the typical clover-leaf structure, except trnS1 which has a reduced DHU arm and the acceptor stem of trnR is 5 or 6 bp in some species, an unusual feature here reported for the first time in Typhlocybinae. The A + T-rich region is highly variable in length and in numbers of tandem repeats present. Our analyses indicate that nad6 and atp6 exhibit higher evolutionary rates compared to other PCGs. Phylogenetic analyses by both maximum likelihood and Bayesian methods based on 13 protein-coding genes of 12 species of Typhlocybinae suggest that Zyginellini are paraphyletic with respect to Typhlocybini.

Complete Mitogenomic Structure and Phylogenetic Implications of the Genus Ostrinia (Lepidoptera: Crambidae)

To understand mitogenome characteristics and reveal phylogenetic relationships of the genus Ostrinia, including several notorious pests of great importance for crops, we sequenced the complete mitogenomes of four species: Ostrinia furnacalis (Guenée, 1854), Ostrinia nubilalis (Hübner, 1796), Ostrinia scapulalis (Walker, 1859) and Ostrinia zealis (Guenée, 1854). Results indicate that the four mitogenomes-O. furnacalis, O. nubilalis, O. scapulalis, and O. zealis-are 15,245, 15,248, 15,311, and 15,208 bp in size, respectively. All four mitogenomes are comprised of 37 encoded genes and a control region. All 13 protein-coding genes (PCGs) initiate with ATN and terminate with TAN, with the exception of cox1 that starts with CGA, and cox1, cox2, and nad5 that terminate with an incomplete codon T. All transfer RNA genes (tRNAs) present the typical clover-leaf secondary structure except for the trnS1 (AGN) gene. There are some conserved structural elements in the control region. Our analyses indicate that nad6 and atp6 exhibit higher evolution rates compared to other PCGs. Phylogenetic analyses based on mitogenomes using both maximum likelihood (ML) and Bayesian inference (BI) methods revealed the relationship (O. palustralis + (O. penitalis + (O. zealis + (O. furnacalis + (O. nubilalis + O. scapulalis))))) within Ostrinia.

Characterization of the complete mitochondrial genomes of two species of the genus Aphaena Guérin-Méneville (Hemiptera: Fulgoridae) and its phylogenetic implications

The complete mitochondrial genomes (mitogenomes) of Aphaena (Callidepsa) amabilis and Aphaena (Aphaena) discolor nigrotibiata were sequenced. The mitogenomes of these two species are 16,237 bp and 16,116 bp in length with an A + T content of 77.9% and 77.0%, respectively. Each contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and a control region (A + T-rich region). All PCGs initiate with the standard start codon of ATN and terminate with the complete stop codon of TAA or TAG except for atp6, where nad1 ends with an incomplete T codon. All tRNAs have the typical clover-leaf structure except for trnS1 and trnV which have a reduced DHU arm. Moreover, these two mitogenomes have trnL2, trnR and trnT with an unpaired base in the acceptor stem. The putative A + T-rich region includes multiple types of tandem repeat regions. These phylogenetic analyses are reconstructed based on 13 protein-coding genes of 25 auchenorrhynchan mitogenomes, with both maximum likelihood and Bayesian analyses yielding robust identical phylogenetic trees. These results support a monophyletic Auchenorrhyncha and the relationship (Pyrops + (Lycorma + Aphaena)) within Fulgoridae.