Complete mitochondrial genome of Periplaneta brunnea (Blattodea: Blattidae) and phylogenetic analyses within Blattodea

Abstract The complete mitochondrial genome (mitogenome) of Periplaneta brunnea was sequenced in this study and used to reconstruct the phylogenetic relationship of Blattodea. The circular mitogenome was 15,604 bp long and exhibited typical gene organization and order, consistent with other sequenced Periplaneta mitogenomes. The initiation codon of the P. brunnea COX1 gene was unusual in that no typical ATN or TTG start codon was found. The two longest intergenic spacer sequences found in the P. brunnea mitogenome were 21 and 17 bp long. Twenty-one base spacer had a 4 bp motif (TATT) between tRNA-Glu and tRNA-Met that conservatively displayed in 9 sequenced blattarian mitogenomes. The second spacer was between tRNA-Ser ( UCN ) and NAD1 containing a 7 bp motif (WACTTAA) that was highly conserved in 14 blattarian mitogenomes. The control region showed a relatively fixed motif present in 6 Blattidae mitogenomes, with a big stem-loop structure. Phylogenetic analyses were conducted using site-homogeneous models based on 13 protein-coding genes (PCGs) and two RNA genes. The trees derived from Bayesian inference and maximum likelihood analyses and recovered a relatively stable relationship among major lineages except for the position of Polyphagidae and inter-family relationships of Blaberidae. Analyses supported the monophyly of Blattidae, Blaberidae, Blattellidae, Polyphagidae, Dictyoptera, and the paraphyly of Blattaria. We also found Mantodea was the sister clade to (Blattaria + Isoptera), being the basal position of Dictyoptera in all topologies. Meanwhile, our results also consistently supported that Isoptera should be clustered with Blattaria of Blattodea.