The lemurs don't hybridize. The two ruffed lemur species can reproduce with each other and the offspring can be fertile, but the zoos are all male. The crowned lemurs are both castrated, the black lemur could potentially reproduce with the red fronted brown female, but she's on birth control I presume. Red bellied female is also probably on birth control, but I think they could probably breed with the Black lemur as well. The ringtails are too distantly related to the other species to reproduce
