They are different subgenuses, I believe. If they were in the same subgenus, it would work, such as Camponotus pennsylvanicus and modoc, but not between subgenuses.
Sorry this really triggered me this morning . The Pogonomyrmex ants referred to are different species... not subgenuses. Scientific names are typically just broken down into Genus, which is a rough categorization of similar organisms, followed by the specific epithet, or species name, which identifies a singular species within that genus. Sometimes subspecies are identified, which results in a third name following the specific epithet, Artemisia tridentata tridentata for example. While subgenuses are a thing, they are typically omitted, unless there is a very specific reason for needing it. If subgenuses are included in a name, they appear in parenthesis after the genus, Nereis (Hediste) diversicolor for example. Typically, subgenuses are used by taxonomists to further divide a genus which has many different species associated with it to help keep track of different affinities. That being said, I do not believe there is a subgenus associated with Pogonomyrmex, especially since we can't specifically identify which population RapaNui's ants came from. Again, sorry for this diversion of the conversation.
https://en.wikipedia..._name_(zoology)
http://www.annelida....otax-tutor.html
To the question of the thread, I would keep trying with different pupae and larvae. I know some species of Formica will accept larvae/pupae from other species within their genus. It is likely you just offered pupae that were to mature for your P. rugosus queen's liking. If you have the brood available, you might as well keep trying. The best case is you successfully boost your colony, the worst case is you are out some brood. Make sure to keep coming back and telling us your progress cause I am sure there are others who are interested in your results .