Mitochondrial genomes of genus Atta (Formicidae: Myrmicinae) reveal high gene organization and giant intergenic spacers.

The ants of the genus Atta are considered important pests to agriculture in the Americas, although Atta species are also important contributors to ecosystem functions in the various habitats in which they occur. The aim of this study was to assemble four complete mitochondrial genomes of the genus Atta, construct the phylogenomic tree, and analyze the gene content, order, and organization. The mitogenomes of A. colombica, A. opaciceps, A. texana, and A. sexdens rubropilosa comprise 18,392, 19,257, 19,709, and 19,748 bp, respectively. The four Atta mitogenomes showed the charactistics typical of those of insects, with 13 protein-coding genes, 22 tRNAs, and 2 rRNAs, with genes displayed in the conventional order. Analysis for intergenic spacer regions showed that Atta intergenic spacers are larger than those of the outgroups. Phylogenomic analyses using partial cytochrome oxidase I gene sequences showed similar topologies to previous phylogenetic analyses, with high clade support values. We conclude that Atta mitogenomes are characterized by high conservation in gene order and have giant intergenic spacers in the genus Atta.