A. Limited opportunities for Dispersal B. Defendable space and ability to defend it. In other words, by cooperating, they can increase chance of survival. A. Naked mole rats. One of seven species. There is on Queen.
Workers are actually phenotypically different.
X. Eusocial Crustacean - a few species of snapping shrimp that live in sponges. Important to note, however, that just because a species is haplo-diploid, this does not mean that it will evolve eusociality. Other conditions must also occur such as overlapping generations, limited dispersal, and defensibility.