Separatist societies

Genders (or sexualities) live apart, with little intermingling or only at fixed times.

Maybe one of them doesn't exist, for whatever reasons.)

Matriarchies have women on top, but not necessarily planned that way; maybe the men just died out; maybe it's a bad thing; whatever. Separatism always has the sexes living apart - often, this is in conjunction with a matriarchy, or is a lesbian separatist utopia, but not always.

• Eleanor Arnason. A Woman of the Iron People and Ring of Swords (1993)
• Ursula K. Le Guin. "The Matter of Seggri" (1994)
• Joanna Russ. The Female Man
• Sheri S. Tepper. The Gate to Women's Country
• Sheri S. Tepper. A Plague of Angels (1993) (one community has men and women living separately)

See also:

• List of works featuring intentional communities designed along gender lines - Intentional communities designed by women, however, are just that: they may include men or may not; they may or may not be matriarchies; they may or may not be utopias.
• Plus see all the stories in which the gender ratios are skewed.