They're a bisexual species; the species has two sexes, just as a biplane has two wings. Words can mean more than one thing, scientific words are no exception.
There's nothing on Oddworld.com, but there are other sources of information. It was in one of Paul O'Connor's MO designer diaries. Having said that, it could be that the females are again queens, and that each pod has it's own queen. We know each pod is (at least regarded as) a self-contained family.