The family Pyxicephalidae including two subfamilies (Cacosterninae and Pyxicephalinae) is an ecologically important group of frogs distributed in sub-Saharan Africa. However, its phylogenetic position among the Anura has remained uncertain. The present study determined the complete mitochondrial genome sequence of Pyxicephalus adspersus, the first representative mitochondrial genome from the Pyxicephalinae, and reconstructed the phylogenetic relationships within Ranoidae using 10 mitochondrial protein-coding genes of 59 frog species. The P. adspersus mitochondrial genome showed major gene rearrangement and an exceptionally long length that is not shared with other Ranoidae species. The genome is 24,317 bp in length, and contains 15 protein-coding genes (including extra COX3 and Cyt b genes), four rRNA genes (including extra 12S rRNA and 16S rRNA genes), 29 tRNA genes (including extra tRNALeu (UAG), tRNALeu (UUR), tRNAThr, tRNAPro, tRNAPhe, tRNAVal, tRNAGln genes) and two control regions (CRs). The Dimer-Mitogenome and Tandem duplication and random loss models were used to explain these gene arrangements. Finally, both Bayesian inference and maximum likelihood analyses supported the conclusion that Pyxicephalidae was monophyletic and that Pyxicephalidae was the sister clade of (Petropedetidae + Ptychadenidae).

The order Microcoryphia, commonly known as bristletails, is considered as the most primitive one among living insects. Within this order, two species, Coreamachilis coreanus and C. songi (Machilidae: Machilinae), display the following contrasting reproductive strategies: parthenogenesis occurs in C. coreanus, whereas sexual reproduction is found in C. songi. In the present study, the complete mitogenomes of C. coreanus and C. songi were sequenced to compare their mitogenome structure, analyze relationships within the Microcoryphia, and assess adaptive evolution. The length of the mitogenomes of C. coreanus and C. songi were 15,578 bp and 15,570 bp, respectively, and the gene orders were those of typical insects. A long hairpin structure was found between the ND1 and 16S rRNA genes of both species that seem to be characteristic of Machilinae and Petrobiinae species. Phylogenetic assessment of Coreamachilis was conducted using BI and ML analyses with concatenated nucleotide sequences of the 13 protein-coding genes. The results showed that the monophyly of Machilidae, Machilinae, and Petrobiinae was not supported. The genus Coreamachilis (C. coreanus and C. songi) was a sister clade to Allopsontus helanensis, and then the clade of ((C. coreanus + C. songi) + A. helanensis) was a sister clade to A. baii, which suggests that the monophyly of Allopsontus was not supported. Positive selection analysis of the 13 protein-coding genes failed to reveal any positive selection in C. coreanus or C. songi. The long hairpin structures found in Machilinae and Petrobiinae were highly consistent with the phylogenetic results and could potentially be used as an additional molecular characteristic to further discuss relationships within the Microcoryphia.

2019) The characteristics and phylogenetic relationship of two complete mitochondrial genomes of Matronabasilaris (Odonata: Zygoptera: Calopterygidae), ABSTRACTThe relationship of Matrona and Atrocalopteryx (Odonata: Calopterygidae) is still unclear. To better understand the phylogenetic relationship of Matrona and Atrocalopteryx, we sequenced and annotated two complete mitochondrial genomes of Matrona basilaris sampled from two different locations. The length of the two complete mitochondrial genomes of M. basilaris is 16,149 bp and 15,893 bp for the specimens collected in Jinhua, Zhejiang Province and Tianmushan, Zhejiang Province, China, respectively. The two mitochondrial genomes include the typical invertebrate set of 37 genes: 13 protein-coding genes (PGCs), 22 tRNA genes, and 2 rRNA genes. The nucleotide composition of the mitogenome is similar to other odonates with high content of A þ T (68.9%) and all PCGs use ATN as the start codon. Tandem repeats were detected in the control regions of the two M. basilaris samples that accounted for the different sequence lengths of the mitochondrial genomes from the two locations. Finally, BI and ML phylogenetic analysis based on the concatenated nucleotide sequences of the 13 PCGs supported the conclusion that M. basilaris is a sister clade to Atrocalopteryx melli. ) and RAxML 8.2.0 (Stamatakis 2014), respectively. Both BI and ML phylogenetic trees showed that M. basilaris is a sister clade to Atrocalopteryx melli. However, the monophyly of Atrocalopteryx failed because M. basilaris is clustered into Atrocalopteryx.

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The complete mitochondrial genome of Pedetontus zhejiangensis (Microcoryphia: Machilidae) was successfully sequenced. The mitochondrial genome of P. zhejiangensis was a circular molecule of 15,602 bp in length, containing 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and the control region, which showed the typical insect mitochondrial genome arrangement. The AT content of the whole genome was 73.8% and the length of the control region was 671 bp with 82.5% AT content. In BI and ML phylogenetic trees, P. zhejiangensis was a sister group to Pedetontus silvestrii, and the monophyly of Pedetontus was strongly supported. The genus Pedetontinus was a sister group to Pedetontus.