Comparative mitochondrial genomes of four species of Sinopodisma and phylogenetic implications (Orthoptera, Melanoplinae)

The Fast Evolution of the Stenobothrini Grasshoppers (Orthoptera, Acrididae, and Gomphocerinae) Revealed by an Analysis of the Control Region of mtDNA, with an Emphasis on the Stenobothrus eurasius Group

The two cryptic grasshopper species of the genus Stenobothrus, S. eurasius and S. hyalosuperficies, demonstrate different acoustic behavior despite a strong similarity in morphology. A hybridization between these species is possible in the contact zone; however, there are little molecular data about the relationships of these species. The analysis of the mtDNA control region (CR) reveals that haplotypes of S. hyalosuperficies have more in common with the more distant Stenobothrus species than with the closely related S. eurasius. In the contact zone, S. eurasius has mt-haplotypes shared with S. hyalosuperficies, which might indicate an introgression of mtDNA from S. hyalosuperficies to the S. eurasius gene pool. We also analyze the structure and evolutionary rate of the mtDNA CR for the Stenobothrus genus and estimate the time of divergence of the species within the genus. The phylogenetic tree of the tribe Stenobothrini reconstructed with either the CR or COI gave the same four groups. The phylogenetic tree of the Stenobothrus genus has a star-like topology with each mtDNA haplotype found in any analyzed species, except S. eurasius, which forms a separate branch. The maximum degree of incomplete lineage sorting can demonstrate either ancestral polymorphism or introgression.

Variation of the Tegmen and Cercus in Sinopodisma rostellocerca (Orthoptera: Acrididae: Melanoplinae) with Proposal of a New Synonym

Intraspecific variation is ubiquitous from individual traits to population level and plays an important role in a variety of fields. However, it is often ignored by systematists and comparative evolutionary biologists. In view of the limited knowledge of intraspecific variation, morphology-based identification has hindered the recognition of species borders and led to a great number of problems in the field of taxonomy and systematics. In this study, the intraspecific variation of the tegmen and cercus in Sinopodisma rostellocerca was examined, the variation patterns were summarized and the relationship between S. rostellocerca and S. hengshanica was discussed. The results showed that the intraspecific variation in the tegmen and male cercus was mainly manifested in the length and shape of the apical margin and dorso- and ventro-apical angles; this substantial variation occurred not only among intrapopulation individuals but also between the different sides of the same individuals, and all types of variation in S. hengshanica fell into the range of variation in S. rostellocerca, leading to the disappearance of the boundary between the two species. Therefore, S. hengshanica was herein considered as a new junior synonym of S. rostellocerca.

The complete mitochondrial genome of Phymateus saxosus (Coquerel, 1861) (Orthoptera: Pyrgomorphidae) and phylogenetic analysis

Phymateus saxosus is a member of the family Pyrgomorphidae, Orthoptera. In this study, the complete mitochondrial genome (mitogenome) of P. saxosus was determined and analyzed. Assembled mitogenome sequence of P. saxosus is 15,672 bp in size, containing 37 genes and a control region. The gene orientation and arrangement of P. saxosus are identical to other species in the Pyrgomorphoidea family. The overall nucleotide composition is as follows: A (43.6%) > T (30.2%) > C (16.1%) > G (10.1%). Phylogenetic analysis suggested that P. saxosus forms sister groups with P. morbillosus, and the monophyly of Pyrgomorphidae is supported. In general, this study provided valuable genetic information for P. saxosus and explored the phylogenetic relationships in the family Pyrgomorphidae.

Two Complete Mitochondrial Genomes of Leptobrachium (Anura: Megophryidae: Leptobrachiinae): Characteristics, Population Divergences, and Phylogenetic Implications

The mustache toads Leptobrachium boringii and Leptobrachium liui are two attractive species in Megophryidae, in which adult males have mustache-like keratinized nuptial spines on their upper lip. However, both are under threat due to multiple factors, of which scientific studies are still very limited. In this study, two new complete mitochondrial genomes of L. boringii and L. liui were sequenced, assembled, and annotated based on next-generation sequencing. The mitogenome lengths of L. boringii and L. liui were found to be 17,100 and 17,501 bp, respectively, with both containing 13 protein coding genes, 23 tRNAs, 2 rRNAs, and 1 non-coding control region. Nucleotide diversity analyses indicate that atp8, atp6, and nad2 showed higher nucleotide diversity than cox1, cox3, and cytb. The intraspecific genetic distances among three different populations of L. boringii exceed 4%, and those between two populations of L. liui reach 7%. Phylogenetic relationships support their division into two subfamilies of Megophryidae (Leptobrachiinae and Megophryinae) as well as two species groups within Leptobrachium, corresponding to the number of keratinized nuptial spines (10-48 in the L. boringii species group vs. 2-6 in the L. liui species group). The two new mitogenomes reported in this study provide valuable data for future molecular evolutionary and conservation studies of the genus Leptobrachium and other Megophryidae toads.

Characterization of the Complete Mitochondrial Genome of a Flea Beetle Luperomorpha xanthodera (Coleoptera: Chrysomelidae: Galerucinae) and Phylogenetic Analysis

In this study, the mitochondrial genome of Luperomorpha xanthodera was assembled and annotated, which is a circular DNA molecule including 13 protein-coding genes (PCGs), 22 transfer RNA (tRNA) genes, 2 ribosomal RNA genes (12S rRNA and 16S rRNA), and 1388 bp non-coding regions (A + T rich region), measuring 16,021 bp in length. The nucleotide composition of the mitochondrial genome is 41.3% adenine (A), 38.7% thymine (T), 8.4% guanine (G), and 11.6% cytosine (C). Most of the protein-coding genes presented a typical ATN start codon (ATA, ATT, ATC, ATG), except for ND1, which showed the start codon TTG. Three-quarters of the protein-coding genes showed the complete stop codon TAR (TAA, TAG), except the genes COI, COII, ND4, and ND5, which showed incomplete stop codons (T- or TA-). All the tRNA genes have the typical clover-leaf structure, except tRNASer1 (AGN), which has a missing dihydrouridine arm (DHU). The phylogenetic results determined by both maximum likelihood and Bayesian inference methods consistently supported the monophyly of the subfamily Galerucinae and revealed that the subtribe Luperina and genus Monolepta are polyphyletic groups. Meanwhile, the classification status of the genus Luperomorpha is controversial.

The Complete Mitogenomes of Three Grasshopper Species with Special Notes on the Phylogenetic Positions of Some Related Genera

Clarifying phylogenetic position and reconstructing robust phylogeny of groups using various evidences are an eternal theme for taxonomy and systematics. In this study, the complete mitogenomes of Longzhouacris mirabilis, Ranacris albicornis, and Conophyma zhaosuensis were sequenced using next-generation sequencing (NGS), and the characteristics of the mitogenomes are presented briefly. The mitogenomes of the three species are all circular molecules with total lengths of 16,164 bp, 15,720 bp, and 16,190 bp, respectively. The gene structures and orders, as well as the characteristics of the mitogenomes, are similar to those of other published mitogenomes in Caelifera. The phylogeny of the main subfamilies of Acrididae with prosternal process was reconstructed using a selected dataset of mitogenome sequences under maximum likelihood (ML) and Bayesian inference (BI) frameworks. The results showed that the genus Emeiacris consistently fell into the subfamily Melanoplinae rather than Oxyinae, and the genus Choroedocus had the closest relationship with Shirackiacris of the subfamily Eyprepocnemidinae in both phylogenetic trees deduced from mitogenome protein coding genes (PCGs). This finding is entirely consistent with the morphological characters, which indicate that Emeiacris belongs to Melanoplinae and Choroedocus belongs to Eyprepocnemidinae. In addition, the genera Conophymacris and Xiangelilacris, as well as Ranacris and Menglacris, are two pairs of the closest relatives, but their phylogenetic positions need further study to clarify.

Mitogenomic Comparison of the Mole Crickets Gryllotalpidae with the Phylogenetic Implications (Orthoptera: Ensifera)

Owing to limited molecular data, the phylogenetic position of the family Gryllotalpidae is still controversial in the infraorder Gryllidea. Mitochondrial genome (mitogenome) plays a crucial role in reconstructing phylogenetic relationships and revealing the molecular evolution of insects. However, only four mitogenomes have been reported in Gryllotalpidae to date. Herein, we obtained the first mitogenomes of Gryllotalpa henana Cai & Niu, 1998 and the Chinese G. orientalis Burmeister, 1838, made a detailed comparison of all mitogenomes available in Gryllotalpidae and reconstructed the phylogeny of Gryllidea based on mitogenomes using Bayesian inference (BI) and maximum likelihood (ML) methods. The results show that the complete mitogenome sequences of G. henana (15,504 bp) and G. orientalis (15,497 bp) are conserved, both exhibiting the double-stranded circular structure, typical gene content and the ancestral insect gene arrangement. The complete mitogenome of G.henana exhibits the lowest average AT content ever detected in Gryllotalpidae, and even Gryllidea. The gene nad2 of both species has atypical initiation codon GTG. All tRNAs exhibit typical clover-leaf structure, except for trnS1 lacking the dihydrouridine (DHU) arm. A potential stem-loop structure, containing a (T)_n(TC)₂(T)_n sequence, is detected in the control region of all gryllotalpids investigated and is likely related to the replication initiation of the minority strand. The phylogenetic analyses recover the six families of Gryllidea as Gryllotalpidae + (Myrmecophilidae + (Mogoplistidae + (Trigonidiidae + (Phalangopsidae + Gryllidae)))), similar to the trees based on transcriptomic and mitogenomic data. However, the trees are slightly different from the multilocus phylogenies, which show the sister-group relationship of Gryllotalpidae and Myrmecophilidae. The contradictions between mitogenomic and multilocus trees are briefly discussed.

Phylogenetic Position of the Genus Alulacris (Orthoptera: Acrididae: Melanoplinae: Podismini) Revealed by Complete Mitogenome Evidence

Whole mitogenomes are a useful data source for a wide variety of research goals due to the vastly cheaper sequencing cost and the far less demanding high-quality templates. The mitogenome has demonstrated great potential in resolving phylogenetic questions in Orthoptera at different taxonomic scales as well as exploring patterns of molecular and morphological character evolutions. In this study, the complete mitogenome of Alulacrisshilinensis (Zheng, 1977) was sequenced using next-generation sequencing, the characteristics of the mitogenome are presented briefly, and the phylogeny of the Melanoplinae and Catantopinae was reconstructed using a selected dataset of mitogenome sequences under maximum likelihood and Bayesian inference frameworks. The results show that the genus was consistently assigned to the subfamily Melanoplinae rather than Catantopinae in all phylogenetic trees deduced from different datasets under different frameworks, and this finding is entirely consistent with its morphological characters. Therefore, it is more appropriate to place the genus Alulacris in Melanoplinae rather than in Catantopinae.