Pewter Boa

The pewter boa is a designer snake, the combination of the blood boa appearance and the anerythristic appearance.

However, this genetic combination was present in the wild-caught animals. The original wild-caught blood boas apparently also carried a gene for the anerythristic appearance. So when they are bred together, a few pewter boas appear in a litter of blood boas. Some of those blood boas are also het-anerythristic, but the hets are not identifiable.  Both the blood trait and the anerythristic trait are inherited as simple recessive traits.

If you breed a pewter boa to a blood boa, the resulting clutch will be 100% blood boas that also are het for the anerythristic gene. If you breed a pewter boa to a normal boa, all the babies will be normal in appearance and double-hets for both traits. If you breed a pewter boa to an anerythristic boa, all the babies will be anerythristic in appearance and all will be het for the blood trait.