[biomattr]

Rove beetles also parasitize army ants. As soon as army ants existed these beetles we're building backdoors. Of course the ants want to recognize these cheaters and eliminate them. As ant genera diverged over time some relied more on tactile recognition of body shape ('touchers') and others not so much ('sniffers'). The parasites of touchers look like the ant but the sniffers not as much.

https://doi.org/10.1016/j.cub.2017.02.030

Touch is dependent on dopamine but smell not as much. And dopamine producing cells are pigmented. Could improved tactility and pigmentation be linked?