Daughters of a coral dawn

To escape life on a future Earth marred by sexual discrimination close to slavery, a group of hyper-intelligent women (they are part alien) decides to find their own planet to colonize, that must remain unknown to Earth's culture. They succeed, until a spaceship from Earth with three hyper-chauvinist men and one woman from Earth lands on the planet. The men cannot be allowed to stay, but they cannot be allowed to return with news of the planet's...