Exploring the molecular phylogeny of phasmids with whole mitochondrial genome sequences

Phasmids are remarkable mimics of twigs, sticks, and leaves. This extreme adaptation for crypsis can easily lead to the convergent evolution of morphology, making it difficult to establish a taxonomic system of phasmids. Accordingly, there are multiple phylogenetic hypotheses that conflict with each other. Phylogenetic arrangements suggested by molecular data disagree with the morphology-based taxonomy in some instances. We collected 13 phasmatodean species, sequenced their mitochondrial genomes, and recovered their molecular phylogeny. Our analyses did not support the monophyly of Areolatae or Anareolatae, two major infraorders of Phasmatodea. The position of Neohirasea was also quite different from the conventional taxonomic systems, thus challenging the previously assumed monophyly of the subfamily Lonchodinae. The enigmatic taxon, Timema, was shown to be distantly related to other phasmatodeans.

Research highlights► Mithochondrial Genomes of 13 phasmids are sequenced. ► Neither Areolatae nor Anareolatae were shown to be monophyletic. ► Monophyly of Lonchodinae is also questioned by the position of Neohirasea japonica. ► Phylogenetic position of Timema was unstable due to the nucleotide compositional bias.