Rather light for walnut.

Hmmmm....maybe cherry then? It is darker than that picture makes it look. I am not a woodworker...I just know what I like. I do know the coffee table and end tables are walnut. This corner cupboard though...I don't know. I just got it on Saturday. The backside of those small panels on either side of the drawer are VERY dark. I'll try to take a good close-up of the wood grain when I get home. Thanks!

Put Waterlox on a scrap of Walnut and then see how it matches. In my experience, walnut lightens a bit over time. The UV rays seem to bleach it out a little bit, but that takes many years. I've pulled apart Walnut wainscoting and found slightly darker shades under the trim pieces, leading me to that assertion.

New black walnut is going to take decades to develop that beautiful dark honey color in the photo.
You could try bleaching the new pieces to take out the chocolate-brown color, then carefully toning it to golden with a very judicious application of stain followed by garnet shellac. I'd try three parts provincial (or ipswitch pine) and one part red mahogany for starters.
Casey

Thanks you for your input. I examined the piece more last night and am fairly certain it is walnut. The backside of the doors and drawer front is very dark.....like you'd expect Walnut to be. I think it's just lightened up with age as Aiden suggested. I am getting the scrap walnut back from my furniture maker and will do some serious experimentation with it to see if I can come up with a nice color. I do love the look of walnut so I may just waterlox it and not stain it at all. I suppose it is not at all important for the new tables to match this corner cupboard. Again.....thanks for the suggestions and guidance.

" I do love the look of walnut so I may just waterlox it and not stain it at all. "

I think you are on the right track.