@f0x A lot of non-male speculative fiction writers use male pen names, so you've probably read a bunch already :) You'd think the (very valid) reasons for this might've become obsolete by now, but unfortunately not.
@f0x Here's a massive list of pen names (in general) to browse http://www.scifi.darkroastedblend.com/2007/08/authors-pseudonyms.html
Readers' gender bias is still very prevalent in the spec fic genre, sadly. (in others too, but this seems to be the worst?) -even though indie pub is slowly changing things, somewhat. But I guess as long as research shows that male/ambiguous author names sell better, the bias will prevail.
Generalistic and moderated instance.