Morphological evolution among obligately myrmecophilous mealybugs

Ants have the potential to influence the morphological evolution of species they partner with in an obligatory mutualism. Strong selective pressures can be imposed upon a trophobiotic partner through an ant’s control over their dispersal and reproduction. We discuss novelties in the morphology of root mealybugs (Rhizoecidae and Xenococcidae) associated with Acropyga ants (Formicidae: Formicinae) and compare them to the morphology of Allomyrmococcini (Pseudococcidae), associated with herdsmen ants from the Dolichoderus cuspidatus species-group (Formicidae: Dolichoderinae). Both qualitative evidence drawn from taxonomic study and quantitative evidence from linear and geometric morphometric analyses show convergence in body shape and size and point out other interesting patterns concerning characteristics of legs and ostiole development. We discuss these patterns of morphological evolution among independently evolving lineages in the context of their phylogeny. These discoveries are a valuable contribution to the body of work cataloguing domestication in non-human agricultural systems.