The mitochondrial genomes are one of the most information-rich markers in phylogenetics. The relationships within superorder Dictyoptera have been debated in the literature. However, the closely related termites (Isoptera) are retained as unranked taxon within the order Blattaria (cockroaches). In this work, we sequenced the complete mitogenomes of two cockroaches, reconstructed the molecular phylogeny and attempted to infer the phylogenetic position of termites in Blattaria more reliably. The complete mtDNA nucleotide sequences of the peridomestic American cockroach (Periplaneta americana L.) and the domestic German cockroach (Blattella germanica L.) are 15,025 and 15,584 bp in size, respectively. The genome shares the gene order and orientation with previously known Blattaria mitogenomes. Most tRNAs could be folded into the typical cloverleaf secondary structure, but the tRNA-Ser (AGN) of P. americana appears to be missing the dihydrouridine arm. Using nucleotide and amino acid sequences as phylogenetic markers, we proposed that termites should be treated as a superfamily (Termitoidea) of cockroaches. We suggested that Polyphagoidea was the sister group of Termitoidea in Blattaria and supported that the suborder Caelifera is more closely related to the Phasmatodea than to the suborder Ensifera of Orthoptera.

Fifteen sequences from the mitochondrial cytochrome c oxidase subunit I gene (COI) were determined for 4 species of the genus Meretrix, with the homologous sequences of M. petechialis obtained from the GenBank data library. The alignment length of the sequences was 574 bp after excluding ambiguous sites, including 93 parsimony informative sites. In the fragments, the percentages of A, T, C and G were 21.15%, 44.71%, 14.05% and 20.09% respectively. There were 12 haplotypes identified:

In this work, we sequenced the complete mitochondrial genome of Blaberoidea species, Blattella bisignata. The circle genome (16,470 bp) consists of 13 protein-coding, 22 tRNA, and 2 rRNA genes, and an A+T-rich region. The A+T-rich region, which contains five long repeat sequences, is located between the small rRNA and tRNA(Ile) and is 1705 bp in length.