The first two mitochondrial genomes from Taeniopterygidae (Insecta: Plecoptera): Structural features and phylogenetic implications

The complete mitochondrial genome of Leucoptera coffeella (Lepidoptera: Lyonetiidae) and phylogenetic relationships within the Yponomeutoidea superfamily

The coffee leaf miner (Leucoptera coffeella) is one of the major pests of coffee crops in the neotropical regions, and causes major economic losses. Few molecular data are available to identify this pest and advances in the knowledge of the genome of L. coffeella will contribute to improving pest identification and also clarify taxonomy of this microlepidoptera. L. coffeella DNA was extracted and sequenced using PacBio HiFi technology. Here we report the complete L. coffeella circular mitochondrial genome (16,407 bp) assembled using Aladin software. We found a total of 37 genes, including 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), 2 ribosomal RNA genes (rRNAs) and an A + T rich-region and a D-loop. The L. coffeella mitochondrial gene organization is highly conserved with similarities to lepidopteran mitochondrial gene rearrangements (trnM-trnI-trnQ). We concatenated the 13 PCG to construct a phylogenetic tree and inferred the relationship between L. coffeella and other lepidopteran species. L. coffeella is found in the Lyonetiidae clade together with L. malifoliella and Lyonetia clerkella, both leaf miners. Interestingly, this clade is assigned in the Yponomeutoidea superfamily together with Gracillariidae, and both superfamilies displayed species with leaf-mining feeding habits.

Mitochondrial genomes provide insights into the Euholognatha (Insecta: Plecoptera)

BACKGROUND

Euholognatha is a monophyletic group within stoneflies comprised by a superfamily Nemouroidea and a family Scopuridae. Based on morphological data, the family-level phylogenetic relationships within Euholognatha are widely accepted, but there is still controversy among different molecular studies. To better understand the phylogeny of all six extant euholognathan families, we sequenced and analyzed seven euholognathan mitogenomes.

RESULTS

The sequence heterogeneity analysis observed a low degree of compositional heterogeneity in euholognathan mitogenomes. Meanwhile, leuctrid mitogenomes were more heterogeneous than other euholognathan families, which may affect the phylogenetic reconstruction. Phylogenetic analyses with various datasets generated three topologies. The Leuctridae was recovered as the earliest branching lineage, and the sister relationship of Capniidae and Taeniopterygidae was supported by most tree topologies and FcLM analyses. When separately excluding sparsely sampled Scopuridae or high heterogeneity leuctrid taxa, phylogenetic analyses under the same methods generated more stable and consistent tree topologies. Finally, based on the results of this study, we reconstructed the relationships within Euholognatha as: Leuctridae + (Scopuridae + ((Taeniopterygidae + Capniidae) + (Nemouridae + Notonemouridae))).

CONCLUSION

Our research shows the potential of data optimizing strategies in reconstructing phylogeny within Euholognatha and provides new insight into the phylogeny of this group.

Comparative Mitochondrial Genomes between the Genera Amiota and Phortica (Diptera: Drosophilidae) with Evolutionary Insights into D-Loop Sequence Variability

To address the limited number of mitochondrial genomes (mitogenomes) in the subfamily Steganinae (Diptera: Drosophilidae), we assembled 12 complete mitogenomes for six representative species in the genus Amiota and six representative species in the genus Phortica. We performed a series of comparative and phylogenetic analyses for these 12 Steganinae mitogenomes, paying special attention to the commonalities and differences in the D-loop sequences. Primarily determined by the lengths of the D-loop regions, the sizes of the Amiota and Phortica mitogenomes ranged from 16,143-16,803 bp and 15,933-16,290 bp, respectively. Our results indicated that the sizes of genes and intergenic nucleotides (IGNs), codon usage and amino acid usage, compositional skewness levels, evolutionary rates of protein-coding genes (PCGs), and D-loop sequence variability all showed unambiguous genus-specific characteristics and provided novel insights into the evolutionary implications between and within Amiota and Phortica. Most of the consensus motifs were found downstream of the D-loop regions, and some of them showed distinct genus-specific patterns. In addition, the D-loop sequences were phylogenetically informative as the data sets of PCGs and/or rRNAs, especially within the genus Phortica.

The First Complete Mitochondrial Genome of Genus Isocapnia (Plecoptera: Capniidae) and Phylogenetic Assignment of Superfamily Nemouroidea

Capniidae are a family of stoneflies, also known as snow flies, who emerge in winter. The phylogeny of Capniidae is widely accepted to be based on morphological analysis. Until now, only five Capniidae mitochondrial genomes have been sequenced so far. In addition, sampling is required to determine an accurate phylogenetic association because the generic classification of this family is still controversial and needs to be investigated further. In this study, the first mitogenome of genus Isocapnia was sequenced with a length of 16,200 bp and contained 37 genes, including a control region, two rRNAs, 22 tRNAs, and 13 PCGs, respectively. Twelve PCGs originated with the common start codon ATN (ATG, ATA, or ATT), while nad5 used GTG. Eleven PCGs had TAN (TAA or TAG) as their last codon; however, cox1 and nad5 had T as their final codon due to a shortened termination codon. All tRNA genes demonstrated the cloverleaf structure, which is distinctive for metazoans excluding the tRNASer1 (AGN) that missed the dihydrouridine arm. A Phylogenetic analysis of the superfamily Nemouroidea was constructed using thirteen PCGs from 32 formerly sequenced Plecoptera species. The Bayesian inference and maximum likelihood phylogeny tree structures derived similar results across the thirteen PCGs. Our findings strongly supported Leuctridae + ((Capniidae + Taeniopterygidae) + (Nemouridae + Notonemouridae)). Ultimately, the best well-supported generic phylogenetic relationship within Capniidae is as follows; (Isocapnia + (Capnia + Zwicknia) + (Apteroperla + Mesocapnia)). These findings will enable us to better understand the evolutionary relationships within the superfamily Nemouroidea and the generic classification and mitogenome structure of the family Capniidae.

New Synonym and New Species Record of Filchneria (Plecoptera: Perlodidae) from China with a Morphological, Phylogenetic and Biogeographic Study on This Genus

The type species of Filchneria Klapálek, 1908, F. mongolica (Klapálek, 1901), is based on a single female collected from Mongolia, but it was considered the same as another species, F. songi from Qinling, China, when the genus Filchneria was proposed. This study narrates the story of these two species, which have been confused for a century. Until now, the distribution of F. mongolica has been confirmed only in Mongolia and Russia, and we recently recorded it for the first time in Inner Mongolia as a new species record in China. Additionally, the genus Sinoperlodes is a junior synonym of Filchneria, as demonstrated by both the morphological and molecular analysis. Phylogenetic analysis based on the subfamily Perlodinae is provided, along with morphological and biogeographic comparisons of Filchneria and its relatives.

New Synonym and New Species Record of Filchneria (Plecoptera: Perlodidae) from China with a Morphological, Phylogenetic and Biogeographic Study on This Genus

The type species of Filchneria Klapálek, 1908, F. mongolica (Klapálek, 1901), is based on a single female collected from Mongolia, but it was considered the same as another species, F. songi from Qinling, China, when the genus Filchneria was proposed. This study narrates the story of these two species, which have been confused for a century. Until now, the distribution of F. mongolica has been confirmed only in Mongolia and Russia, and we recently recorded it for the first time in Inner Mongolia as a new species record in China. Additionally, the genus Sinoperlodes is a junior synonym of Filchneria, as demonstrated by both the morphological and molecular analysis. Phylogenetic analysis based on the subfamily Perlodinae is provided, along with morphological and biogeographic comparisons of Filchneria and its relatives.

Characterization of Seventeen Complete Mitochondrial Genomes: Structural Features and Phylogenetic Implications of the Lepidopteran Insects

Lepidoptera (moths and butterflies) are widely distributed in the world, but high-level phylogeny in Lepidoptera remains uncertain. More mitochondrial genome (mitogenome) data can help to conduct comprehensive analysis and construct a robust phylogenetic tree. Here, we sequenced and annotated 17 complete moth mitogenomes and made comparative analysis with other moths. The gene order of trnM-trnI-trnQ in 17 moths was different from trnI-trnQ-trnM of ancestral insects. The number, type, and order of genes were consistent with reported moths. The length of newly sequenced complete mitogenomes ranged from 14,231 bp of Rhagastis albomarginatus to 15,756 bp of Numenes albofascia. These moth mitogenomes were typically with high A+T contents varied from 76.0% to 81.7% and exhibited negative GC skews. Among 13 protein coding genes (PCGs), some unusual initiations and terminations were found in part of newly sequenced moth mitogenomes. Three conserved gene-overlapping regions and one conserved intergenic region were detected among 17 mitogenomes. The phylogenetic relationship of major superfamilies in Macroheterocera was as follows: (Bombycoidea + Lasiocampoidea) + ((Drepanoidea + Geometroidea) + Noctuoidea)), which was different from previous studies. Moreover, the topology of Noctuoidea as (Notodontidae + (Erebidae + Noctuidae)) was supported by high Bayesian posterior probabilities (BPP = 1.0) and bootstrapping values (BSV = 100). This study greatly enriched the mitogenome database of moth and strengthened the high-level phylogenetic relationships of Lepidoptera.

The mitochondrial genome analysis of a stonefly, Nemoura longicercia Okamoto, 1922 (Plecoptera: Nemouridae)

To better understand the diversity and phylogeny of Nemouridae, we sequenced and annotated the complete mitochondrial genome (mitogenome) of Nemoura longicercia Okamoto, 1922. The entire mitochondrial genome of N. longicercia was 15,728 bp. It contained 37 representative genes (22 transfer RNA genes (tRNAs), 13 protein-coding genes (PCGs), and two ribosomal RNA genes (rRNAs)) and a control region. In this genome, 23 genes were found on the heavy strand (H-strand) and 14 genes were on the light strand (L-strand). All PCGs began with the initiation codon ATN. Eleven PCGs stopped with the termination codon TAA or TAG, while COII and ND5 genes stopped with incomplete codon T. Bayesian’s inference (BI) and maximum-likelihood (ML) methods generated the identical tree topology across the PCGR dataset (13 PCGs plus two rRNAs). The monophyly of each subfamily was well-supported. This analysis supported the clade N. longicercia plus N. papilla as sister taxon to the clade N. meniscata plus N. nankinensis.

Mitochondrial Genome of Strophopteryx fasciata (Plecoptera: Taeniopterygidae), with a Phylogenetic Analysis of Nemouroidea

Taeniopterygidae is a medium-sized family of stoneflies. The phylogeny of Taeniopterygidae was widely accepted based on the morphological analyses. However, there are different opinions based on molecular data. To date, only two taeniopterygid mitochondrial genomes (mitogenomes) were available, and more sampling is needed to obtain precise phylogenetic relationships. In this research, the Strophopteryx fasciata mitogenome was sequenced and analyzed. The complete mitogenome of S. fasciata was 15,527 bp in length and contained 37 genes and a non-coding control region. Among taeniopterygid mitogenomes, the length variation was minimal in protein-coding genes (PCGs), transfer RNA genes (tRNAs) and ribosomal RNA genes (rRNAs), but very different in the control region. Similar to mitogenomes of other taeniopterygid species, the S. fasciata mitogenome was consistently AT biased and displayed positive AT- and negative GC-skews of the whole mitogenome. Most PCGs used ATN as the start codon and TAA/TAG as the stop codon. The stop codons were far less variable than the start codons in taeniopterygid mitogenomes. All Ka/Ks ratios were less than 1, indicating the presence of purifying selection in these genes. The secondary structures of transfer and ribosomal RNA genes of S. fasciata mitogenome are highly conserved with other taeniopterygid species. In the control region of the S. fasciata mitogenome, some essential elements (tandem repeats, stem–loop structures, and poly−N stretch, etc.) were observed. Two phylogenetic trees were inferred from Bayesian inference (BI) and Maximum Likelihood (ML) methods generated the identical topology across the PCGR dataset. The relationships of five families in Nemouroidea were recovered as Leuctridae + ((Capniidae + Taeniopterygidae) + (Nemouridae + Notonemouridae)). These results will help us understand the mitogenome structure of taeniopterygid species and the evolutionary relationship within Plecoptera.

Mitochondrial Genomes of the Genus Claassenia (Plecoptera: Perlidae) and Phylogenetic Assignment to Subfamily Perlinae

Mitochondrial genomes of three stoneflies, e.g., Claassenia magna Wu, 1948, Claassenia sp. 2 and Claassenia xucheni Chen, 2019 were sequenced in this study with 15,774, 15,777 and 15,746 bp in length, respectively. Each mitogenome contained 37 genes including 22 tRNAs, two ribosomal RNAs, 13 protein-coding genes (PCGs), and a noncoding control region (CR). In general, standard ATN start and TAN termination codons were evident in the PCGs. Although the dihydrouridine arm was absent in trnSer, the remaining 21 tRNAs displayed the characteristic cloverleaf secondary structure. Stem-loop structures were identified in the CRs of all three mitogenomes, but tandem repeats were only apparent in Claassenia xucheni. The mitogenomes of three Claassenia species were analyzed and compared with mitogenomes in 21 other stoneflies from the Perlidae and three Euholognatha species (Rhopalopsole bulbifera, Capnia zijinshana and Amphinemura longispina) as outgroups. Phylogenetic analyses using maximum likelihood and Bayesian inference. Phylogenetic analysis supported that Claassenia was recovered as the sister group of other Perlinae and Claassenia+Perlinae emerged from the paraphyletic Acroneuriinae. The final results supported that Claassenia was classified into subfamily Perlinae and proposed Claassenia represent a transitional group of the subfamilies Acroneuriinae and Perlinae. This study provided new molecular evidence for exploring the debatable taxonomic position of the genus Claassenia in Perlidae.

Complete mitochondrial genome and phylogenetic position of Filchneria songi in Perlodidae (Insecta: Plecoptera)

The complete mitochondrial genome of the perlodid stonefly, Filchneria songi Chen, 2019 was sequenced and analyzed. This double strand, circular molecule is 16,028 bp in length with an A + T content of 70.1%, and contains 13 PCGs, 22 tRNA genes, and two rRNA genes. A 1099-bp long control region was detected, with a high A + T content of 81.9%. Gene arrangement was conserved in the mitogenome of F. songi. Most PCGs use standard start codons and ended with complete stop codons. The phylogenetic analysis supported that F. songi was closely related with species of Perlodes Banks, 1903.

Two Complete Mitochondrial Genomes From Leuctridae (Plecoptera: Nemouroidea): Implications for the Phylogenetic Relationships Among Stoneflies

The family-level relationships within Plecoptera have been a focused area of research for a long time. Its higher classification remains unstable, and the phylogenetic relationships within Plecoptera should be re-examined. Here, we sequenced and analyzed two complete mitochondrial genomes (mitogenomes) of Paraleuctra cercia and Perlomyia isobeae of the family Leuctridae. We reconstructed the phylogeny of Plecoptera based on 13 protein-coding genes (PCGs) from published stoneflies. Our results showed that the Bayesian inference and maximum-likelihood tree had similar topological structures except for the positions of two families, Peltoperlidae and Scopuridae. The Plecoptera is divided into two clades, the suborder Antarctoperlaria and the suborder Arctoperlaria. The two suborders subsequently formed two groups, Eusthenioidea and Gripopterygoidea, and Euholognatha and Systellognatha, which is consistent with the results of morphological studies. In addition, the Leuctridae is the earliest branch within the superfamily Nemouroidea. But the monophyly of Perloidea and Pteronarcyoidea are still not well supported.

Molecular phylogeny inferred from the mitochondrial genomes of Plecoptera with Oyamia nigribasis (Plecoptera: Perlidae)

In this study, the mitochondrial genome of the stonefly, Oyamia nigribasis Banks, 1920 (Plecoptera: Perlidae), was sequenced and compared with the mtDNA genomes of 38 other stoneflies and two Ephemerae. The O. nigribasis mitogenome is a circular 15,923 bp molecule that encodes a large, noncoding control region (CR) and 37 typical mtDNA genes; these include 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), and two ribosomal RNA genes (rRNAs), respectively. Most of the PCGs initiated with ATN and terminated with TAN. The dihydrouridine (DHU) arm of tRNASer (AGN) was missing, whereas the other 21 tRNAs all exhibited the typical cloverleaf secondary structure. Stem-loop (SL) structures and tandem repeats were identified in the CR. Phylogenetic analyses using Bayesian inference and maximum likelihood were undertaken to determine relationships between stoneflies. Results indicated that the Antarctoperlaria, which contains Gripopterygidae, was absolutely separated from Arctoperlaria; this finding agrees with morphology. Finally, the overall relationships could be summarized as follows ((((Notonemouridae + Nemouridae) + Leuctridae) + (Scopuridae + (Capniidae + Taeniopterygidae))) + (((Perlodidae + Chloroperlidae) + Perlidae) + (Pteronarcyidae + (Peltoperlidae + Styloperlidae))) + ((Diamphipnoidae + Eustheniidae) + Gripopterygidae)).

The complete mitochondrial genome of Flavoperla biocellata Chu, 1929 (Plecoptera: Perlidae) and the phylogenetic analyses of Plecoptera

Of the roughly 400 species of Perlidae in the world, most species are widely distributed in the northern hemisphere, but a few can be found in South Africa and South America. There are only five species in the genus Flavoperla of the family Perlidae in China. To gain a better understanding of the architecture and evolution of mitochondrial genome in Flavoperla, the entire mitochondrial genome (mitogenome) of a Chinese Flavoperla biocellata Chu, 1929 from family Perlidae (Insecta: Plecoptera) was sequenced. The 15,805-bp long mitochondrial genome of F. biocellata contained 37 genes, including 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and a putative control region (CR). The gene arrangement of F. biocellata was identical with that of other stoneflies and with the fly Drosophila yakuba. Most PCGs of F. biocellata used the standard ATN start codons and complete TAN termination codons. Twenty-one of the 22 tRNA genes exhibited cloverleaf secondary structures, but the dihydrouridine (DHU) arm of trnSer (AGN) was completely reduced. Phylogenetic analyses with both Bayesian inference (BI) and maximum likelihood methods (ML) generated similar topology, both supporting the monophyly of all stonefly families and the infraorder Systellognatha. The phylogenetic analysis based on mitochondrial genomic data from 30 stonefly species recovered a well-supported tree resolving higher-level relationships within Plecoptera. The northern hemisphere suborder Arctoperlaria divided into two groups, Euholognatha and Systellognatha. The southern hemisphere suborder Antarctoperlaria formed two clades: Eustheniidae+Diamphipnoidae and Austroperlidae+ Gripopterygidae; consistent with relationships proposed based on morphology. The final relationships within Plecoptera were recovered as (((Perlidae+(Perlodidae+Chloroperlidae))+(Pteronarcyidae+(Peltoperlidae+Styloperlidae))) +(Taeniopterygidae+(Capniidae+(Nemouridae+Notonemouridae))))+ (Gripopterygoidae+Eusthenioidae).

Characterization of the complete mitochondrial genome of Nemoura meniscata Li & yang (Plecoptera: Nemouridae) from China

We sequenced the third complete mitochondrial genome of Nemoura meniscataby using the high-throughput sequencing method. The mitochondrial genome harbored 37 typical code genes and a control region with 15,895 bp in length was a double-stranded and circular genome. The nucleotide composition is partial to A and T. Seventy-eight nucleotides were dispersed in 10 intergenic spacers and gene overlaps were also found at 13 gene junctions with 48 nucleotides. In phylogenetic trees, the 13 Nemouridae species form a clade diverged from the outgroup clade. The genus Nemoura and Amphinemura were sister groups which is consistent with the previous study.

First mitochondrial genome from Yponomeutidae (Lepidoptera, Yponomeutoidea) and the phylogenetic analysis for Lepidoptera

The complete mitochondrial genome (mitogenome) of Yponomeuta montanatus is sequenced and compared with other published yponomeutoid mitogenomes. The mitogenome is circular, 15,349 bp long, and includes the typical metazoan mitochondrial genes (13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes) and an A + T-rich region. All 13 protein-coding genes use a typical start codon ATN, the one exception being cox1, which uses CGA across yponomeutoid mitogenomes. Comparative analyses further show that the secondary structures of tRNAs are conserved, including loss of the Dihydorouidine (DHU) arm in trnS1 (AGN), but remarkable nucleotide variation has occurred mainly in the DHU arms and pseudouridine (TψC) loops. A + T-rich regions exhibit substantial length variation among yponomeutoid mitogenomes, and conserved sequence blocks are recognized but some of them are not present in all species. Multiple phylogenetic analyses confirm the position of Y. montanatus in Yponomeutoidea. However, the superfamily-level relationships in the Macroheterocera clade in Lepidoptera recovered herein show considerable difference with that recovered in previous mitogenomic studies, raising the necessity of extensive phylogenetic investigation when more mitogenomes become available for this clade.

The first mitochondrial genome of the family Epicopeiidae and higher-level phylogeny of Macroheterocera (Lepidoptera: Ditrysia)

The Macroheterocera clade contains most of the Lepidoptera species. However, extensive comparative and phylogenetic analyses of this group using complete mitochondrial genomes (mitogenome) are limited particularly in the context of increasing macroheteroceran mitogenomes reported to date. In this study, complete mitogenome of the Epicopeia hainesii is determined as the first Epicopeiidae species with mitogenome available. The whole mitogenome is circular with 15,395 bp long, and is highly biased toward A + T nucleotides (80.6%) in nucleotide composition. Comparative analyses show that gene content and arrangement of macroheteroceran mitogenomes are generally conservative and are typical of Lepidoptera but exceptions exist. In newly sequenced mitogenome, the motif "ATACTAA" is putatively located at the end of gene nad1, rather than in intergenic sequences between trnS2 and nad1 genes routinely observed in Lepidoptera. Interestingly, multiple phylogenetic analyses recover the six macroheteroceran superfamilies as Mimallonoidea + (Drepanoidea + ((Bombycoidea + Lasiocampoidea) + (Noctuoidea + Geometroidea))), providing supports for a large-scale transcriptomic study rather than various mitogenome- and multiple-gene-based investigations. In addition, our analyses consistently place the Epicopeiidae as sister group with Geometroidea, firstly demonstrating that this family is closer with Geometroidea than Drepanoidea based on mitogenome data.

Mitochondrial genomes of the stoneflies Mesonemourametafiligera and Mesonemouratritaenia (Plecoptera, Nemouridae), with a phylogenetic analysis of Nemouroidea

In this study, two new mitochondrial genomes (mitogenomes) of Mesonemourametafiligera and Mesonemouratritaenia from the family Nemouridae (Insecta: Plecoptera) were sequenced. The Mesonemourametafiligera mitogenome was a 15,739 bp circular DNA molecule, which was smaller than that of M.tritaenia (15,778 bp) due to differences in the size of the A+T-rich region. Results show that gene content, gene arrangement, base composition, and codon usage were highly conserved in two species. Ka/Ks ratios analyses of protein-coding genes revealed that the highest and lowest rates were found in ND6 and COI and that all these genes were evolving under purifying selection. All tRNA genes in nemourid mitogenomes had a typical cloverleaf secondary structure, except for tRNA^Ser(AGN) which appeared to lack the dihydrouridine arm. The multiple alignments of nemourid lrRNA and srRNA genes showed that sequences of three species were highly conserved. All the A+T-rich region included tandem repeats regions and stem-loop structures. The phylogenetic analyses using Bayesian inference (BI) and maximum likelihood methods (ML) generated identical results. Amphinemurinae and Nemourinae were sister-groups and the family Nemouridae was placed as sister to Capniidae and Taeniopterygidae.

The phylogeny and evolutionary timescale of stoneflies (Insecta: Plecoptera) inferred from mitochondrial genomes

Phylogenetic analysis based on mitochondrial genomic data from 25 stonefly species recovered a well-supported tree resolving higher-level relationships within Plecoptera (stoneflies). The monophyly of both currently recognized suborders was strongly supported, concordant with previous molecular analyses of Plecoptera. The southern hemisphere suborder Antarctoperlaria formed two clades: Eustheniidae + Diamphipnoidae and Austroperlidae + Gripopterygidae; consistent with relationships proposed based on morphology. The largely northern hemisphere suborder Arctoperlaria also divided into two groups, Euholognatha and Systellognatha, each composed of the five families traditionally assigned to each infraorder (the placement Scopuridae by mt genome data remains untested at this time). Within Euholognatha, strong support for the clade Nemouridae + Notonemouridae confirmed the northern origin of the currently southern hemisphere restricted Notonemouridae. Other family level relationships within the Arctoperlaria differ from those recovered by previous morphology and molecular based analyses. A fossil-calibrated divergence estimation suggests the formation of two suborders dates back to the Jurassic (181 Ma), with subsequent diversification of most stonefly families during the Cretaceous. This result confirms the hypothesis that initial divergence between the suborders was driven by the breakup of the supercontinent Pangaea into Laurasia and Gondwanaland (commencing 200 Ma and complete by 150 Ma).

The first mitochondrial genome from Scopuridae (Insecta: Plecoptera) reveals structural features and phylogenetic implications

This study determined the first complete mitochondrial genome (mitogenome) of a stonefly, Scopura longa (Plecoptera: Scopuridae), and reconstructed a phylogeny based on two datasets of mitogenomes in eighteen available stoneflies to examine the relationships among Plecoptera. The complete mitogenome of S. longa is a circular molecule of 15,798bp in size. It contains 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs) and a control region (CR). Most PCGs used standard ATN start codons and TAN stop codons. All tRNAs could be folded as typical cloverleaf secondary structures except tRNA^Ser(AGN), with the dihydrouridine (DHU) arm missing. Tandem repeat regions, two potential stem-loop (SL) structures, Poly T structures and G+C-rich regions are detected in the control region. Finally, the phylogenetic relationships among the families within the Arctoperlaria were reconstructed. The topological structures of the two trees were almost identical. The present phylogenetic analysis shows that S. longa belongs to the infraorder Euholognatha. The monophyly of each family is generally well supported based on nucleotide sequences. The Pteronarcyidae is sister to ((Peltoperlidae+Styloperlidae)+(Perlidae+(Perlodidae+Chloroperlidae))).

The complete mitochondrial genome of a medicinal insect, Hydrillodes repugnalis (Lepidoptera: Noctuoidea: Erebidae), and related phylogenetic analysis

The complete mitochondrial genome (mitogenome) of an important medicinal insect Hydrillodes repugnalis (Lepidoptera: Noctuoidea) was sequenced and analyzed. The mitogenome is circular with 15,570 bp long, and shows typical gene content and arrangement. Nucleotide composition is highly biased toward A + T nucleotides (81.1%). All protein-coding genes (PCGs) initiate with canonical start codon ATN, except for cox1 being CGA. The typical stop codon TAA is used for most PCGs, while the nad4l uses the TAG, and cox1 and cox2 use incomplete termination codon T. All tRNAs have a typical clover-leaf structure, except for trnS1 (AGN) lacking the dihydrouridine arm. Comparative mitogenome analysis showed that the motif "ATGATAA" between atp8 and atp6, and the motif "ATACTAA" between trnS2 and nad1 are commonly present in noctuoid mitogenomes. In A + T-rich regions, the motif "ATAGA" and subsequent poly-T structure, the motif "ATTTA" and followed macrosatellite (AT)_n element and an "A"-rich 3' end upstream of the trnM gene can be recognized across noctuoid mitogenomes. Phylogenetic analyses showed that H. repugnalis is nested into the Erebidae clade, consistently being sister to the Aganainae. Within Noctuoidea, the (Notodontidae + (Erebidae + (Nolidae + (Euteliidae + Noctuidae)))) was consistently recovered firstly based on multiple mitochondrial datasets.

Complete Mitochondrial Genome of Suwallia teleckojensis (Plecoptera: Chloroperlidae) and Implications for the Higher Phylogeny of Stoneflies

Stoneflies comprise an ancient group of insects, but the phylogenetic position of Plecoptera and phylogenetic relations within Plecoptera have long been controversial, and more molecular data is required to reconstruct precise phylogeny. Herein, we present the complete mitogenome of a stonefly, Suwallia teleckojensis, which is 16146 bp in length and consists of 13 protein-coding genes (PCGs), 2 ribosomal RNAs (rRNAs), 22 transfer RNAs (tRNAs) and a control region (CR). Most PCGs initiate with the standard start codon ATN. However, ND5 and ND1 started with GTG and TTG. Typical termination codons TAA and TAG were found in eleven PCGs, and the remaining two PCGs (COII and ND5) have incomplete termination codons. All transfer RNA genes (tRNAs) have the classic cloverleaf secondary structures, with the exception of tRNASer(AGN), which lacks the dihydrouridine (DHU) arm. Secondary structures of the two ribosomal RNAs were shown referring to previous models. A large tandem repeat region, two potential stem-loop (SL) structures, Poly N structure (2 poly-A, 1 poly-T and 1 poly-C), and four conserved sequence blocks (CSBs) were detected in the control region. Finally, both maximum likelihood (ML) and Bayesian inference (BI) analyses suggested that the Capniidae was monophyletic, and the other five stonefly families form a monophyletic group. In this study, S. teleckojensis was closely related to Sweltsa longistyla, and Chloroperlidae and Perlidae were herein supported to be a sister group.