Characterization of the complete mitochondrial genomes of four tarantulas (Arachnida: Theraphosidae) with phylogenetic analysis

To better understand the evolution of mitochondrial genomes (mitogenomes) within the family Theraphosidae, we characterized mitogenomes of four tarantulas (Grammostola pulchripes, Phormictopus atrichomatus, Pterinochilus murinus and Pterinopelma sazimai) for the first time. The mitogenomes were all classical circular structures, with lengths ranging from 13,822 bp to 14,011 bp. The constitutive genes and the orientation of the coding strand observed in the four mitogenomes were consistent with those found in other species belonging to the Theraphosidae family. The four mitogenomes were compacted and exhibited a preference for A and T, with the rRNA sequences showing a higher A+T content. Ka/Ks and p-distances analyses showed the ND6 gene had highest evolutionary rate, while the COⅠ gene displayed relatively slower evolution. In contrast to previous phylogenetic studies, our phylogenetic analysis based on mitogenomes provides new phylogenetic relationships among subfamilies. Subfamily Theraphosinae is most closely related to Ornithoctoninae, slightly distant from Harpactirinae, and farthest from Selenocosmiinae. The new data we acquired regarding these mitogenomes will aid in understanding the complex interrelationships among species within the Theraphosidae family.