I e-mailed the Grazianis about this last year. This is the response I got from Greg:
In 2002, we obtained a Piebald male that sired 2 clutches of eggs in 2005. Out of 14 offspring 7 were visual Leopards. With a 50% ratio we knew we were working with a new dominant gene. The name Leopard was assigned to this gene because of the leopard yellow color that was created when the Leopard Pastel and Leopard Spiders were produced in 2005.
In 2009, we produced 6 clutches of Leopard x Leopard for a total of 26 offspring. Out of the 26 offspring 21 were Leopards. There was no visual super form produced. Due to that fact we are considering the leopard gene to be dominant not co-dominant. The one question we have yet to answer is, “Can the Leopard gene be isolated from the Piebald gene or are all Leopards 100% Het Piebalds?” To answer this we will have to produce a large number of offspring from the Leopard Possible Het Piebalds and see if they all produce Piebalds.
We believe that the Leopards are all 100% het Piebalds. Our reasoning is the leopard pattern resembles the Piebald pattern. Our theory is there are 2, Piebald genes that are compatible, however one of the Piebald genes is on the same allele as the Leopard gene. If this is the case the genes cannot be separated, making all Leopards Het Piebalds. Only future breeding will prove of disprove our theory! Either way this is an exciting new project to be working with!!!!