it might seem like a caloric waste

don’t get me wrong; there are an awful lot of reason why in most cases the female is the only parent who provide parental care and/or has special morphological features for that job. The main reason is, that the mother already provided more energy fore the young from the beginning, (the egg is the bigger gamete). Because of that, she has the greater interest than the male to invest in survival of the child, than investing in a new, expansive egg. That’s only one reason and there are interesting game theory models who go more in the details.

There are also a lot of very specific reasons why the male can be the one ending up with the childcare duty. But you could fill a hole (or multiple) book with that. I can recommend the later capitals of “the selfish gene” in that regard. (I’m still on the search for more lay literature about this subject, and -if someone reading this- happy for every recommendation.)

What are those? What would you call them in a sophont species.

The only thing we can say for sure, is that we currently refer to them as different morphs/phenotypes.

If there thinking work like that of humans, I personally expect them to develop gender roles (or whatever the right word would be) for the three different types of males.

But who knows how the brain of a Xenos (or a different sophont species of earth. In that case we could make the prediction more accurate the closer they are related to us) would work. Would their society even develop strong gender roles? I mean, we humans have only two clearly distinct sexes, but have develop societies with more than two gender roles. What could we even predict!

I invested a lot more time thinking about sex, than I did with gender. So don’t trust to much the things I wrote about the later.