Sequence and phylogenetic analysis of the complete mitochondrial genome of the flour beetle Tribolium castanaeum

We describe the first complete mitochondrial genome sequence from a representative of the insect order Coleoptera, the flour beetle Tribolium castaneum. The 15,881 bp long Tribolium mitochondrial genome encodes 13 putative proteins, two ribosomal RNAs and 22 tRNAs canonical for animal mitochondrial genomes. Their arrangement is identical to that in Drosophila melanogaster, which is considered ancestral for insects and crustaceans (Boore et al., 1998; Hwang, et al., 2001a). Nucleotide composition, amino acid composition, and codon usage fall within the range of values observed in other insect mitochondrial genomes. Most notable features are the use of TCT as tRNA(Ser(AGN)) anticodon instead of GCT, which is used in most other arthropod species, and the relative scarcity of special sequence motifs in the 1431 bp long control region. Phylogenetic analysis confirmed resolving power in the conserved regions of the mitochondrial proteome regarding diversification events, which predate the emergence of pterygote insects, while little resolution was obtained at the level of basal perygote diversification. The partition of faster evolving amino acid sites harbored strong support for joining Lepidoptera with Diptera, which is consistent with a monophyletic Mecopterida.