I'm still getting acquainted with Yellowbelly myself, but is there a chance the trident headstamp could be attributed to Spotnose? I just hatched a snake with a similar headstamp and I'm thinking mine is Spotnose, maybe Spotnose +? The other genes at play in my case are black pastel and yellowbelly, and the one I think is Yellowbelly doesn't really have a headstamp. Hopefully this is helpful for you.
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