The complete mitochondrial genome of Atelura formicaria (Hexapoda: Zygentoma) and the phylogenetic relationships of basal insects.

In this study, the complete sequence of the mitochondrial DNA (mtDNA) of Atelura formicaria (Hexapoda: Zygentoma) is described. The molecule is 15.205 bp in length and it is the third complete mt genome sequenced from the Zygentoma. The genome organization conforms with the putative ancestral insect gene arrangement. All protein coding genes use standard initiation codons (methionine and isoleucine). The exception is nad4 that starts with GTG, a codon used for this purpose in other insect species. A peculiar strand skew bias is observed, given that the PCGs encoded on the J-strand contain more thymines than adenines and more cytosines than guanines. This trend in nucleotide composition has been observed also in the "firebrat" Thermobia domestica (Zygentoma, Lepismatidae), but differs from that of the majority of hexapod species, including Tricholepidion gertschi (Zygentoma, Lepidotrichidae), where adenines and cytosines outnumber thymines and guanines. The presence of structural elements in the control region is also discussed, with emphasis on their potential implications in the regulation of replication and/or transcription of the mitochondrial genome. A mitogenomic phylogenetic analysis, centered on the internal relationships within Zygentoma and on the position of Microcoryphia and Zygentoma among Ectognatha, is performed.