I think snakes use the zw sex chromosomes like birds, not the xy like mammals. Further, I think the females are the zw that determines the gender (zz male, zw female) of the offspring.

I know my original spider pair came from the same male spider to two normal girls. I just hatched a spider combo female from a spider female bred to a non spider male last night. There looks to be one more spider combo in the egg, I'll let you know if it happens to be male.

It would be very interesting and unexpected to me (but then what do I know) if somehow a spider sperm can't fertilize a spider egg. But it certainly would explain the results (or lack thereof) seen so far. I think the infertile super spider might be a more precedented explanation so will have to see what tattlife2001 has to say about that (i.e. have all the possible homozygous spiders been able to reproduce or are upwards of 1/3 failing?). If that turns out to be the case would be interesting how to categorize the mutation (is it still co-dominant lethal even if the homozygous looks the same because it is different in that it's removed from the gene pool by being sterile?). Anyway, jumping ahead, will need to hear some numbers on possible homozygous spiders reproducing first.