Characterization of the complete mitochondrial genome of Empoasca sp. (Cicadellidae: Hemiptera)

Sequencing and analysis of the complete mitochondrial genome of Amrasca biguttula biguttula Ishida, 1913 (Hemiptera: Cicadellidae: Typhlocybinae: Empoascini)

The complete mitogenome of the cotton leafhopper, Amrasca biguttula biguttula Ishida, 1913, was sequenced and annotated. The mitogenome is 14,474 bp long and contains 37 genes, including 13 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, and 22 transfer RNA (tRNA) genes, as well as a control region. The nucleotide composition of the mitogenome is as follows: A, 39.17%; T, 39.3%; C, 11.13%; and G, 10.39%. The total length of the 13 PCGs is 10,496 bp, which encodes 3503 amino acids. All PCGs start with the ATG codon, except for ATA, ATC, GTG, and ATT. Most of the PCGs stop with TGA, and the remaining with CCT, GAA, GGT, TCA, CCA, CTA, TTA, AAA, ATT, or ATA. The phylogenetic tree shows that A. biguttula biguttula belongs to Empoascini of the subfamily Typhlocybinae, but is different from other species within the subfamily.

Two new species of Erythroneurini (Hemiptera, Cicadellidae, Typhlocybinae) from southern China based on morphology and complete mitogenomes

Erythroneurine leafhoppers (Hemiptera, Cicadellidae, Typhlocybinae, Erythroneurini) are utilized to resolve the relationship between the four erythroneurine leafhopper (Hemiptera, Cicadellidae, Typhlocybinae, Erythroneurini): Arboridia (Arboridia) rongchangensis sp. nov., Thaia (Thaia) jiulongensis sp. nov., Mitjaevia bifurcata Luo, Song & Song, 2021 and Mitjaevia diana Luo, Song & Song, 2021, the two new species are described and illustrated. The mitochondrial gene sequences of these four species were determined to update the mitochondrial genome database of Erythroneurini. The mitochondrial genomes of four species shared high parallelism in nucleotide composition, base composition and gene order, comprising 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs) and an AT control region, which was consistent with majority of species in Cicadellidae; all genes revealed common trait of a positive AT skew and negative GC skew. The mitogenomes of four species were ultra-conservative in structure, and which isanalogous to that of others in size and A + T content. Phylogenetic trees based on the mitogenome data of these species and another 24 species were built employing the maximum likelihood and Bayesian inference methods. The results indicated that the four species belong to the tribe Erythroneurini, M. diana is the sister-group relationship of M. protuberanta + M. bifurcata. The two species Arboridia (Arboridia) rongchangensis sp. nov. and Thaia (Thaia) jiulongensis sp. nov. also have a relatively close genetic relationship with the genus Mitjaevia.

Complete Mitogenome Analysis of Five Leafhopper Species of Idiocerini (Hemiptera: Cicadellidae)

Insect mitochondrial genomes (mitogenomes) are of great interest in exploring molecular evolution, phylogenetics, and biogeography. So far, only 12 mitogenomes of the leafhopper tribe Idiocerini have been released in GenBank, although the tribe comprises 488 known species including some agricultural, forestry, and horticultural pests. In order to compare and analyze the mitochondrial genome structure of Idiocerini and even the selective pressure of 13 protein-coding genes (PCGs) of the family Cicadellidae, the complete mitogenomes of five species including Nabicerus dentimus, Sahlbergotettix salicicola, Podulmorinus opacus, Podulmorinus consimilis, and a new species of a new genus were determined by next-generation sequencing. The size of the newly determined mitogenomes ranged from 14,733 bp to 15,044 bp, comprising the standard set of 13 PCGs, 22 transfer RNA genes, two ribosomal RNA genes, and a long non-coding control region (CR). The extent of purifying selection presented different pictures in the tribe and the family. The less pronounced genes (0.5 < dN/dS < 1) were nad5 and nad4l in Idiocerin, whereas in the family Cicadellidae including the sequences of Idiocerin, nad1-nad6 and cox1 genes were less pronounced. The codon encoding leucine was the most common in all species, and the codon encoding serine 1 was the most common in all species except for P. opacus. Interestingly, in P. opacus, another of the most common codons is that encoding serine 2. Among the 17 examined species of the Idiocerini, 14 species contained the tandem repeats, and 11 species of them contained the motif "TTATA". These findings will promote research on the structure and evolution of the mitochondrial genome and highlight the need for more mitogenomes in Cicadellidae.

Comparison of mitogenomes of three Petalocephala species (Hemiptera: Cicadellidae: Ledrinae) and their phylogenetic analysis

Ledrinae is a unique group of leafhoppers with a distinct appearance. Petalocephala is the largest Ledrinae genus that is difficult to identify except by dissecting the male genitals. To date, research on Ledrinae is relatively less compared with other leafhoppers. Therefore, to better understand this group, we sequenced and analyzed three complete Petalocephala mitochondrial genomes. We comparatively analyzed these general Petalocephala genomic features (including size, AT content, AT/GC skew, 13 protein-coding gene nucleotide compositions, etc.), and predicted 22 transfer RNA secondary structures. We obtained highly consistent phylogenetic results within Cicadellidae based on mitogenomic data using the maximum likelihood and Bayesian methods. Our results showed that all subfamilies were monophyletic and had a high node support rate, and there was a sister group relationship between Ledrinae and all other leafhopper groups. Furthermore, treehoppers were found to originate from leafhoppers and showed sister group relationships with Megophthalminae. Within Ledrinae, all phylogenetic trees supporting phylogenetic relationships were as follows: ([P. dicondylica + P. gongshanensis] + [Tituria pyramidata + [Ledra auditura + P. gongshanensis]]) Based on the complete mitogenome phylogenetic analysis and the comparison of morphological characteristics, we propose that Petalocephala is not monophyletic.

Characterization of the morphology and complete mitochondrial genomes of Eupteryx minusula and Eupteryx gracilirama (Hemiptera: Cicadellidae: Typhlocybinae) from Karst area, Southwest China

Background

The hemipteran insect family Cicadellidae (leafhoppers) includes >2,600 valid genera and >22,000 valid species worldwide, including >2,000 species in China. Typhlocybinae, second largest subfamilies of Cicadellidae, is widely distributed in the six major zoogeographic regions of the world, including >4,000 species worldwide and >1,000 species in China. Previously, morphological analysis are often effective to the way of taxonomy, but it did not combine with molecular biology. Therefore, morphology and mitochondrial genomes (mitogenomes) of two leafhopper species, Eupteryx (Eupteryx) minusculaLindberg, 1929 and Eupteryx (Stacla) graciliramaHou, Zhang & Huang, 2016 were studied and analyzed. This study analyzed the morphological and molecular characteristics of the two leafhoppers, and showed whether the results of the two identifications were consistent.

Methods

Based on the method of comparison, mitogenomes and morphology were analyzed to prove the relationship between the two leafhoppers.

Results

Although two focal species are classified in two different subgenera of the same genus, they still share many morphological features, such as the moderately produced crown fore margin; the milky yellow apical part of scutellum; the pronotum, basal triangles of scutellum, and forewing are dark with several colorless patches on the surface; the light yellow face, without any spots or stripes, and so on. The circular mitogenomes are 16,944 bp long in E. minuscula (GenBank: MN910279) and 17,173 bp long in E. gracilirama (GenBank: MT594485). All of the protein-coding genes are starting with ATN, except for some in mitogenome, which has a single T or TAN as a stop codon. All tRNAs have the typical cloverleaf-shaped structure except for trnS1 (AGN) (E. minuscula) which has a reduced DHU arm. Moreover, these two mitogenomes have trnR with an unpaired base in the acceptor stem. The phylogenetic relationships between E. minuscula and E. gracilirama in respect to related lineages were reconstructed using Maximum likelihood and Maximum parsimony analyses.

Discussion

The result showed that the tribe Typhlocybini is a sister to the tribes Erythroneurini and Empoascini, and five genera, Bolanusoides, Typhlocyba, Eupteryx, Zyginella and Limassolla are forming a single clade. E. minuscula and E. gracilirama are clustered together, supporting the monophyly of the genus Eupteryx. The above conclusions are consistent with the traditional classification of the subfamily.

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.

Mitogenome and phylogenetic analysis of typhlocybine leafhoppers (Hemiptera: Cicadellidae)

Mitogenomes have been widely used to estimate phylogenetic relationships among insects and provide data useful for augmenting traditional morphological characters in delimiting species. Here, complete mitogenome sequences of two closely related typhlocybine leafhoppers, Cassianeuracassiae (Ahmed, 1970) and C. bimaculata Dworakowska, 1984, were obtained and found to be 15,423 bp and 14,597 bp in length, respectively. The gene order was found to be similar to other published leafhopper mitogenomes, but the control region of C.bimaculata is the shortest among known leafhoppers and lacks tandem repeats. Phylogenetic analysis of 13 protein-coding genes (PCGs), the first and second codons of 13 PCGs, 13 PCGs and two rRNAs formed three well-supported tree topologies. The topologies of phylogenetic trees inferred from three datasets were almost identical, which was consistent with previous molecular phylogenies of this group. Comparative morphological study of the ovipositors revealed several characters potentially useful for diagnosing genera and resolving their phylogenetic relationships. Phylogenetic analysis of these and other morphological characters yielded a tree that is mostly consistent with the tree obtained from analysis of mitogenome sequences. In both molecular and morphological phylogenenies, Typhlocybini and Zyginellini clustered into one clade, but neither was recovered as monophyletic.

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.

Characterization of Two Complete Mitochondrial Genomes of Ledrinae (Hemiptera: Cicadellidae) and Phylogenetic Analysis

Mitochondrial genomes are widely used for investigations into phylogeny, phylogeography, and population genetics. More than 70 mitogenomes have been sequenced for the diverse hemipteran superfamily Membracoidea, but only one partial and two complete mtgenomes mitochondrial genomes have been sequenced for the included subfamily Ledrinae. Here, the complete mitochondrial genomes (mitogenomes) of two additional Ledrinae species are newly sequenced and comparatively analyzed. Results show both mitogenomes are circular, double-stranded molecules, with lengths of 14,927 bp (Tituria sagittata) and 14,918 bp (Petalocephala chlorophana). The gene order of these two newly sequenced Ledrinae is highly conserved and typical of members of Membracoidea. Similar tandem repeats in the control region were discovered in Ledrinae. Among 13 protein-coding genes (PCGs) of reported Ledrinae mitogenomes, analyses of the sliding window, nucleotide diversity, and nonsynonymous substitution (Ka)/synonymous substitution (Ks) indicate atp8 is a comparatively fast-evolving gene, while cox1 is the slowest. Phylogenetic relationships were also reconstructed for the superfamily Membracoidea based on expanded sampling and gene data from GenBank. This study shows that all subfamilies (sensu lato) are recovered as monophyletic. In agreement with previous studies, these results indicate that leafhoppers (Cicadellidae) are paraphyletic with respect to the two recognized families of treehoppers (Aetalionidae and Membracidae). Relationships within Ledrinae were recovered as (Ledra + (Petalocephala + Tituria)).

Characterization of the complete mitochondrial genome of Mitjaevia protuberanta（Hemiptera: Cicadellidae: Typhlocybinae）

The complete mitogenome of Mitjaevia protuberanta (GenBank accession number MN627216) is 14,032 bp (AT: 77.43%) in length, including 13 protein-coding, 22 transfer RNAs, and 2 ribosomal RNAs. All protein-coding genes used ATN as initiation codon except ND5 that used TTG as initiation codon, and TAA, TAG, and T were termination codons. We constructed a phylogenetic tree from 14 species (Hemiptera) based on the nucleotide sequence of 13 mitochondrial protein-coding genes. The phylogenetic analysis results showed that mitochondrial genome of M. protuberanta had the same characteristics as other Cicadellidae species.