The complete mitochondrial genome ofPyxicephalus adspersus: high gene rearrangement and phylogenetics of one of the world’s largest frogs

Abstract

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 ofPyxicephalus 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. TheP. adspersusmitochondrial 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 extraCOX3andCyt bgenes), four rRNA genes (including extra12S rRNAand16S rRNAgenes), 29 tRNA genes (including extratRNALeu(UAG),tRNALeu(UUR),tRNAThr,tRNAPro,tRNAPhe,tRNAVal,tRNAGlngenes) 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).