Poul Anderson's Virgin
From the Publisher
Three centuries ago, a ship carrying women to a colony world was marooned
on an uncharted planet. Reproducing by parthenogenesis, which produces
only female offspring, the survivors told their descendents that someday
others would come to the world they named Atlantis—including men.
As centuries passed, the legendary creatures called men have taken
on a godlike aspect. And when a lone space explorer discovers Atlantis,
the women know he can't possibly be a man—he's just a monster who looks
like a deformed woman. But he has advanced knowledge that the nations of
Atlantis want, and are willing to go to war with each other to obtain.