Could be anigre, I used that in a couple recent builds and the color and grain look right, that has more figuring than what I had. However I'm not sure I've ever seen anigre in a commercial build.
Did you check out Ken's website? He has a gallery of many of his builds and information about them. Lots of eye candy as well.
Thanks for the comments. I was actually the original owner. Sold the bass a decade ago. I ordered it with a Walnut burl top without really knowing back then what I'm ordering, therefor never questioned about it. I think it's clear it isn't Walnut... just curios what it is. I don't have it and don't know where it is today.
Any other photos? Walnut covers a few species with sometimes radically different appearances. Especially once you talk about burl and potential hybrid or graft Lumber. If you're familiar with one species, seeing another one might make you think it wasn't walnut.
I vote maple burl... maybe myrtle burl. Those markings certainly appear to be some sort of burl... and it doesn't look like cat puke, so we know it's not buckeye burl.
"Top Wood" is my English game show name. (Note my good taste in not claiming it's my British stripper name.)
Has it potentially seen a lot of sun? Walnut heartwood will take on a honey tone like that from UV. At any rate it's hard to tell what it is. But it is certainly beautiful. If I was sold that bass and told by the builder it was walnut burl I'd probably just accept that at face value. It does look fairly light in color but it's not inexplicable. Here's a walnut burl Lakland on reverb that looks really close: Lakland 55-94 2017 Natural Walnut Burl | Russell's Bass Shop
If he’s still in business contact him. It really could be any one of several species of wood. Having said that, there is something to it that makes me think it could be stained figured birch. The colour and the figure reminds me of what was occasionally used in the making of “federal card tables” back in the 1800’sl
Ironically, stained birch was used in furniture during that era as a way to imitate other more expensive lumber, like walnut!