Complete mitochondrial genomes of two green lacewings, Chrysoperla nipponensis (Okamoto, 1914) and Apochrysa matsumurae Okamoto, 1912 (Neuroptera: Chrysopidae)

Characterization of the complete mitochondrial genome of the Libelloides sibiricus (Neuroptera, Ascalaphidae)

Libelloides sibiricus (Eversmann, 1850) is widely distributed in China, Korea and eastern Russia. To date, few studies have been conducted on this species, with the exception of morphological taxonomy studies. In this study, we sequenced the complete mitochondrial genome (mitogenome) of Libelloides sibiricus, which is 15,811 bp in length, with an overall A + T content of 74.8%, encoding 2 ribosomal RNA genes, 22 transfer RNA genes, 13 protein-coding genes, and a control region. The gene arrangement and components of L. sibiricus are identical to those of most other Neuropteran species. TAA is utilized as the termination codon for most PCGs and TAG for nd1, however, nd6 and atp6 used the incomplete termination codon TA- and cox1, cox2, nd5, cytb had termination codons consisting of only T-. In addition, we selected all known 59 species of Neuroptera from NCBI, and used Sialis hamata, Sialis melania, Sialis longidens and Sialis jiyuni (Megaloptera: Sialidae) as the outgroup. Phylogenetic analysis suggested that the mitogenome of L. sibiricus was the most closely related to L. macaronius and all the owlflies formed the monophyletic group within the superfamily Myrmeleontoidea.

New Mitogenomes of the Green Lacewing Tribe Ankylopterygini (Neuroptera: Chrysopidae: Chrysopinae) and Phylogenetic Implications of Chrysopidae

Chrysopidae (green lacewings) are a cosmopolitan and species-rich family of Neuroptera, with remarkable significance of biological control against various agricultural and forestry pests. However, the phylogenetic position of Chrysopidae in Neuroptera and the internal relationships within the family remain equivocal among previous studies based on different types of data and sampling. Here we sequenced the mitochondrial genomes (mitogenomes) of two species of the genus Ankylopteryx in the chrysopine tribe Ankylopterygini for the first time. The characteristics of these mitogenomes were analyzed in comparison with other green lacewing mitogenomes published to date. In the phylogeny herein reconstructed based on mitogenomes, Chrysopinae were recovered as the sister group to Apochrysinae + Nothochrysinae. Within the subfamily of Chrysopinae, Nothancylini were recovered as the sister group to (Leucochrysini + Belonopterygini) + (Ankylopterygini + Chrysopini). The divergence time estimation suggested an Early Cretaceous initial divergence within the extant Chrysopidae. Within Chrysopinae, the four tribes except Nothancylini diverged around mid-Cretaceous.

The complete mitochondrial genome of Hemerobius spodipennis (Neuroptera: Hemerobiidae)

The complete mitochondrial genome of Hemerobius spodipennis Yang, 1987 was sequenced in this study. The complete mitochondrial genome is a typical double-stranded circular molecule of 16,343 bp (GenBank accession number: MT268963) comprising of 13 protein-coding genes, 22 transfer RNA genes, 2 ribosomal RNA genes, and a control region. The gene order is identical to that of the putative ancestral arrangement of insects and other lacewings. All protein-coding genes initiate with ATN, except COI use CGA as start codons and terminate with TAG or TAA, expect ND5 and ND4 use TA– or a single T–– residue as the stop codon. All tRNAs, ranging from 63 to 72 bp, can be folded into typical clover-leaf secondary structure except for tRNA^Ser(AGN), in which the dihydrouridine (DHU) arm did not form a stable stem-loop structure. The control region is 1433 bp long with an A + T content of 91.4%. In the sampled families of Neuroptera, each family showed a monophyletic cluster and Polystoechotidae + Rapismatidae, Hemerobiidae + (Chrysopidae + (Polystoechotidae + Rapismatidae)), are recovered in phylogenetic analyses with high supports.

The complete mitochondrial genome of Hemerobius japonicus (Neuroptera: Hemerobiidae)

The complete mitochondrial genome of Hemerobius japonicus Nakahara, 1915 was sequenced in this study. The complete mitochondrial genome is a typical double-stranded circular molecule of 18,585 bp (GenBank accession number: MN852445), containing 37 typical animal mitochondrial gene and an A + T-rich region. The gene order is identical to that of the putative ancestral arrangement of insects and other lacewings. 13 protein-coding genes (PCGs) possessed common triplet initiation codons ATN except ND1 possessed TTG and mostly terminated with TAN codons except for ND5 and ND4 with a single T residue adjacent to a downstream tRNA gene. All of the 22 tRNAs, ranging from 63 to 72 bp, can be folded into classic clover-leaf secondary structure except for tRNA^Ser(AGN), in which the dihydrouridine (DHU) arm did not form a stable stem-loop structure. The control region is 1416 bp long with an A + T content of 90.3%. In the sampled families of Neuroptera, each family showed a monophyletic cluster and Polystoechotidae + Rapismatidae, Osmylidae + the remaining families, Hemerobiidae + (Chrysopidae + (Polystoechotidae + Rapismatidae)) are recovered in phylogenetic analyses with high supports.

The complete mitochondrial genome of the soldier fly Ptecticus aurifer

The pig body was put in the wild area in summer for collecting sarcosaphagous insects. After 31-day (9 June 2015 to 9 July 2015), the pig body was to be mummification. Ptecticus aurifer (Walker 1854) was found as sarcosaphagous insect for the first time. The complete mitochondrial genome of P. aurifer (Walker 1854) was sequenced in this study. The complete mitochondrial genome is a typical double-stranded circular molecule of 15,775 bp (GenBank accession number: MN604259) containing 37 typical animal mitochondrial gene and an A + T-rich region. 11 of the 22 tRNAs, ranging from 63 to 72 bp, can be folded into classic clover-leaf secondary structure except for tRNA^Ser(AGN), in which the dihydrouridine (DHU) arm did not form a stable stem-loop structure. The control region is 954 bp long with an A + T content of 90.7%.

Characteristics of the complete mitochondrial genome of Suhpalacsa longialata (Neuroptera, Ascalaphidae) and its phylogenetic implications

The owlflies (Family Ascalaphidae) belong to the Neuroptera but are often mistaken as dragonflies because of morphological characters. To date, only three mitochondrial genomes of Ascalaphidae, namely Libelloides macaronius; Ascaloptynx appendiculatus; Ascalohybris subjacens, are published in GenBank, meaning that they are greatly under-represented in comparison with the 430 described species reported in this family. In this study, we sequenced and described the complete mitochondrial genome of Suhpalacsa longialata (Neuroptera, Ascalaphidae). The total length of the S. longialata mitogenome was 15,911 bp, which is the longest known to date among the available family members of Ascalaphidae. However, the size of each gene was similar to the other three Ascalaphidae species. The S. longialata mitogenome included a transposition of tRNACys and tRNATrp genes and formed an unusual gene arrangement tRNACys-tRNATrp-tRNATyr (CWY). It is likely that the transposition occurred by a duplication of both genes followed by random loss of partial duplicated genes. The nucleotide composition of the S. longialata mitogenome was as follows: A = 41.0%, T = 33.8%, C = 15.5%, G = 9.7%. Both Bayesian inference and ML analyses strongly supported S. longialata as a sister clade to (Ascalohybris subjacens + L. macaronius), and indicated that Ascalaphidae is not monophyletic.

Phylogenetic relationships among tribes of the green lacewing subfamily Chrysopinae recovered based on mitochondrial phylogenomics

Chrysopidae (green lacewings) is the second largest family in Neuroptera, and it includes medium-size lacewings largely recognized by the presence of golden-colored eyes, bright green bodies and delicate wings with dense venation patterns. The subfamily Chrysopinae includes 97% of the species diversity in the family and it is currently divided into four tribes: Ankylopterygini, Belonopterygini, Chrysopini and Leucochrysini. Here we sequenced and annotated the nearly complete mitochondrial genomes of four species of each these tribes: Abachrysa eureka, Italochrysa insignis, Leucochrysa pretiosa, Parankyloteryx sp. We then reconstructed the phylogenetic relationships with estimated divergence times among tribes of Chrysopinae based on the mt genomic data. Our results suggest that Chrysopinae sans Nothancyla verreauxi evolved as two reciprocally monophyletic lineages formed by stem members of the tribes Leucochrysini plus Belonopterygini on one hand, and the stem members of Ankylopterygini plus Chrysopini on the other. Our estimations of divergence times place the diversification of stem Chrysopinae into the extant tribes during the Middle Jurassic to Late Cretaceous. The relatively young ages previously estimated for the green lacewing divergences were probably underestimated due to false inferences of homology between non-sister taxa that are later correctly identified as homoplasy after more taxa are added.

Characterization of the complete mitogenomes of two Neoscona spiders (Araneae: Araneidae) and its phylogenetic implications

The complete mitogenomes of two orb-weaving spiders Neoscona doenitzi and Neoscona nautica were determined and a comparative mitogenomic analysis was performed to depict evolutionary trends of spider mitogenomes. The circular mitogenomes are 14,161bp with A+T content of 74.6% in N. doenitzi and 14,049bp with A+T content of 78.8% in N. nautica, respectively. Both mitogenomes contain a standard set of 37 genes typically presented in metazoans. Gene content and orientation are identical to all previously sequenced spider mitogenomes, while gene order is rearranged by tRNAs translocation when compared with the putative ancestral gene arrangement pattern presented by Limulus polyphemus. A comparative mitogenomic analysis reveals that the nucleotide composition bias is obviously divergent between spiders in suborder Opisthothelae and Mesothelae. The loss of D-arm in the trnS(UCN) among all of Opisthothelae spiders highly suggested that this common feature is a synapomorphy for entire suborder Opisthothelae. Moreover, the trnS(AGN) in araneoids preferred to use TCT as an anticodon rather than the typical anticodon GCT. Phylogenetic analysis based on the 13 protein-coding gene sequences consistently yields trees that nest the two Neoscona spiders within Araneidae and recover superfamily Araneoidea as a monophyletic group. The molecular information acquired from the results of this study should be very useful for future research on mitogenomic evolution and genetic diversities in spiders.

First complete mitochondrial genome from the brown lacewings (Neuroptera: Hemerobiidae)

The first complete mitochondrial genome of the family Hemerobiidae (Neuronema laminatum Tjeder, 1936) is sequenced in this study. The complete mitochondrial genome is a typical double-stranded circular molecule of 17,164 bp (GenBank accession number: KR078257) containing 37 typical animal mitochondrial gene and an A + T-rich region. The gene order is identical to that of the putative ancestral arrangement of insects and other lacewings. Thirteen protein-coding genes (PCGs) possessed common triplet initiation codons ATN and mostly terminate with TAN codons except for ND5 with a single T residue adjacent to a downstream tRNA gene. All the 22 tRNAs, ranging from 63 to 72 bp, can be folded into classic clover-leaf secondary structure except for tRNA(Ser(AGN)), in which the dihydrouridine (DHU) arm did not form a stable stem-loop structure. The control region is 2131 bp long with an A + T content of 87.4%. In the sampled families of Neuroptera, Osmylidae + the remaining families, Hemerobiidae + Mantispidae, Polystoechotidae + Rapismatidae, are recovered in phylogenetic analyses with high supports.

The complete mitochondrial genome of the Chrysoperla sinica (Tjeder)

The complete mitochondrial genome of the Chrysoperla sinica was sequenced in this study. It is 16,057 bp in length, and contains 22 transfer RNA genes, 13 protein-coding genes (PCGs), 2 rRNA genes and 1 non-coding AT-rich region. But, C. sinica lack long tandem repeats. The Chrysoperla sinica mitogenome displays a very high level of similarity (99.27%) with Chrysoperla nipponensis. The genome base composition is 39.24% A, 39.70% T, 11.98% C, and 9.08% G. Similar to other insects, all PCGs are initiated by a typical ATN codon, except COX1, which starts with TCG. Nine PCGs have the standard, complete stop codon (TAA or TAG), and the other four PCGs end with the incomplete stop codon (TA or T).

The first mitochondrial genomes of antlion (Neuroptera: Myrmeleontidae) and split-footed lacewing (Neuroptera: Nymphidae), with phylogenetic implications of Myrmeleontiformia

In the holometabolous insect order Neuroptera (lacewings), the cosmopolitan Myrmeleontidae (antlions) are the most species-rich family, while the closely related Nymphidae (split-footed lacewings) are a small endemic family from the Australian-Malesian region. Both families belong to the suborder Myrmeleontiformia, within which controversial hypotheses on the interfamilial phylogenetic relationships exist. Herein, we describe the complete mitochondrial (mt) genomes of an antlion (Myrmeleon immanis Walker, 1853) and a split-footed lacewing (Nymphes myrmeleonoides Leach, 1814), representing the first mt genomes for both families. These mt genomes are relatively small (respectively composed of 15,799 and 15,713 bp) compared to other lacewing mt genomes, and comprise 37 genes (13 protein coding genes, 22 tRNA genes and two rRNA genes). The arrangement of these two mt genomes is the same as in most derived Neuroptera mt genomes previously sequenced, specifically with a translocation of trnC. The start codons of all PCGs are started by ATN, with an exception of cox1, which is ACG in the M. immanis mt genome and TCG in N. myrmeleonoides. All tRNA genes have a typical clover-leaf structure of mitochondrial tRNA, with the exception of trnS1(AGN). The secondary structures of rrnL and rrnS are similar with those proposed insects and the domain I contains nine helices rather than eight helices, which is common within Neuroptera. A phylogenetic analysis based on the mt genomic data for all Neuropterida sequenced thus far, supports the monophyly of Myrmeleontiformia and the sister relationship between Ascalaphidae and Myrmeleontidae.

Comparative mitogenomic analysis reveals sexual dimorphism in a rare Montane lacewing (Insecta: Neuroptera: Ithonidae)

Rapisma McLachlan, 1866 (Neuroptera: Ithonidae) is a rarely encountered genus of lacewings found inmontane tropical or subtropical forests in Oriental Asia. In Xizang Autonomous Region (Tibet) of China there are two sympatrically distributed species of Rapisma, i.e. Rapisma xizangense Yang, 1993 and Rapisma zayuanum Yang, 1993, in which R. xizangense is only known as male and has dull brownish body and wing coloration, while R. zayuanum is only known as female and has bright green body and wing coloration. In order to clarify the relationship between these two species, we determined the complete mitochondrial (mt) genomes of R. xizangense and R. zayuanum for the first time. The mt genomes are 15,961 and 15,984 bp in size, respectively, and comprised 37 genes (13 protein coding genes, 22 tRNA genes and 2 rRNA genes). A major noncoding (control) region was 1,167 bp in R. xizangense and 1,193 bp in R. zayuanum with structural organizations simpler than that reported in other Neuropterida species, notably lacking conserved blocks or long tandem repeats. Besides similar mitogenomic structure, the genetic distance between R. xizangense and R. zayuanum based on two rRNAs and 13 protein coding genes (PCGs) as well as the genetic distance between each of these two Tibetan Rapisma species and a Thai Rapisma species (R. cryptunum) based on partial rrnL show that R. xizangense and R. zayuanum are most likely conspecific. Thus, R. zayuanumsyn. nov. is herein treated as a junior synonym of R. xizangense. The present finding represents a rare example of distinct sexual dimorphism in lacewings. This comparative mitogenomic analysis sheds new light on the identification of rare species with sexual dimorphism and the biology of Neuroptera.

The first mitochondrial genome for caddisfly (insecta: Trichoptera) with phylogenetic implications

The Trichoptera (caddisflies) is a holometabolous insect order with 14,300 described species forming the second most species-rich monophyletic group of animals in freshwater. Hitherto, there is no mitochondrial genome reported of this order. Herein, we describe the complete mitochondrial (mt) genome of a caddisfly species, Eubasilissa regina (McLachlan, 1871). A phylogenomic analysis was carried out based on the mt genomic sequences of 13 mt protein coding genes (PCGs) and two rRNA genes of 24 species belonging to eight holometabolous orders. Both maximum likelihood and Bayesian inference analyses highly support the sister relationship between Trichoptera and Lepidoptera.

Ancestral gene organization in the mitochondrial genome of Thyridosmylus langii (McLachlan, 1870) (Neuroptera: Osmylidae) and implications for lacewing evolution

The first complete mitochondrial genome of the lacewing family Osmylidae (Thyridosmylus langii (McLachlan, 1870)) (Neuroptera) was sequenced in this study. The genome is a circular molecule of 16,221 bp containing the typical 37 genes but is arranged in the same order as that of the putative ancestor of hexapod and lacks translocation of trnC as shared by all previously sequenced neuropteran mtDNAs. This reveals that trnC translocation does not represent an organizational synapomorphy in the mitochondrion for the entire Neuroptera clade. Comparative analysis of neuropteran tRNA genes reveals a relatively slow and conserved evolution of the mitochondrion throughout the order. Secondary structure models of the ribosomal RNA genes of T. langii largely agree with those proposed for other insect orders. Nevertheless, domain I of T. langii rrnL is consisted of nine helices rather than eight helices which is typical for neuropteran rrnL. Protein-coding genes have typical mitochondrial start codons, with the exception of COI, which uses the TCG start codon also found in Ithonidae and Chrysopidae. Like other neuropteran insects, the control region is the most AT-rich region and comparatively simple, with little evidence of conserved blocks or long tandem repeats. Considering the issues of base-compositional and branch length heterogeneity, we used a range of phylogenetic approaches to recover neuropteridan relationships and explored the effect of method choice on recovery of monophyly of Neuropterida: ((Neuroptera + Megaloptera) + Raphidioptera). The monophyly of Neuroptera and the more basal position of Osmylidae were also recovered by different datasets and phylogenetic methods.

Mitochondrial genomes of two Barklice, Psococerastis albimaculata and Longivalvus hyalospilus (Psocoptera: Psocomorpha): contrasting rates in mitochondrial gene rearrangement between major lineages of Psocodea

The superorder Psocodea has ∼10,000 described species in two orders: Psocoptera (barklice and booklice) and Phthiraptera (parasitic lice). One booklouse, Liposcelis bostrychophila and six species of parasitic lice have been sequenced for complete mitochondrial (mt) genomes; these seven species have the most rearranged mt genomes seen in insects. The mt genome of a barklouse, lepidopsocid sp., has also been sequenced and is much less rearranged than those of the booklouse and the parasitic lice. To further understand mt gene rearrangements in the Psocodea, we sequenced the mt genomes of two barklice, Psococerastis albimaculata and Longivalvus hyalospilus, the first representatives from the suborder Psocomorpha, which is the most species-rich suborder of the Psocodea. We found that these two barklice have the least rearranged mt genomes seen in the Psocodea to date: a protein-coding gene (nad3) and five tRNAs (trnN, trnS1, trnE, trnM and trnC) have translocated. Rearrangements of mt genes in these two barklice can be accounted for by two events of tandem duplication followed by random deletions. Phylogenetic analyses of the mt genome sequences support the view that Psocoptera is paraphyletic whereas Phthiraptera is monophyletic. The booklouse, L. bostrychophila (suborder Troctomorpha) is most closely related to the parasitic lice. The barklice (suborders Trogiomorpha and Psocomorpha) are closely related and form a monophyletic group. We conclude that mt gene rearrangement has been substantially faster in the lineage leading to the booklice and the parasitic lice than in the lineage leading to the barklice. Lifestyle change appears to be associated with the contrasting rates in mt gene rearrangements between the two lineages of the Psocodea.

The first mitochondrial genome for the fishfly subfamily Chauliodinae and implications for the higher phylogeny of Megaloptera

Megaloptera are a basal holometabolous insect order with larvae exclusively predacious and aquatic. The evolutionary history of Megaloptera attracts great interest because of its antiquity and important systematic status in Holometabola. However, due to the difficulties identifying morphological apomorphies for the group, controversial hypotheses on the monophyly and higher phylogeny of Megaloptera have been proposed. Herein, we describe the complete mitochondrial (mt) genome of a fishfly species, Neochauliodes punctatolosus Liu & Yang, 2006, representing the first mt genome of the subfamily Chauliodinae. A phylogenomic analysis was carried out based on the mt genomic sequences of 13 mt protein-coding genes (PCGs) and two rRNA genes of nine Neuropterida species, comprising all three orders of Neuropterida and all families and subfamilies of Megaloptera. Both maximum likelihood and Bayesian inference analyses highly support the monophyly of Megaloptera, which was recovered as the sister of Neuroptera. Within Megaloptera, the sister relationship between Corydalinae and Chauliodinae was corroborated. The divergence time estimation suggests that stem lineage of Neuropterida and Coleoptera separated in the Early Permian. The interordinal divergence within Neuropterida might have occurred in the Late Permian.

The complete mitochondrial genome analysis of the tiger (Panthera tigris)

The complete mitochondrial genomes of five tiger samples from three subspecies (P. t. sumatrae, P. t. altica, and P. t. tigris) were successfully obtained by using 26 specifically designed Panthera-specific primer sets. The genome organization and gene arrangement of the five tiger samples were similar to each other; however polymorphic tandem repeat sequences were observed in the control region (CR). This led to a difference in the genome lengths obtained from these five samples with an average size of 16,994 bp for the five tiger mitochondrial genomes. The nucleotide base composition was on average as follows: A, 31.8%; T, 27.0%; C, 26.6%; G, 14.6% and exhibited compositional asymmetry. Most of tiger mitochondrial genome characteristics are similar to those of other common vertebrate species; however, some distinctive features were observed in the CR. First, the repetitive sequence 2 (RS 2) contained two repeat units of 80 bp and the first 15 bp of what would be the third repeat motif. The repetitive sequence 3 (RS 3) contained 47-50 repeat motifs of a shorter 8 bp (ACGTAYAC)(n). Second, length heteroplasmy polycystosine (poly-C) stretches was observed at the end of the HV I locus in all tiger samples.