This moth, or at least one of the series is in BOLD as NEPTA1591-16, specimen page RMNH.INS.24814.
Fresh S. populetorum look like this, males with a yellow abdomen. Caught examples are often paler.
The 32 sequenced specimens are public on BOLD.
What is named S. aromella differs only by a strange structure on the male abdomen, that I have seen in just a few specimens. I don't think it is a specific character, but don't know what it is... Aberrant structure? Fungus? parasite?

That makes sense and kind of what I figured. This came up when I was processing a photo by Jim Vargo which doesn't match, black scales on head vs. orange. He passed along your response that it was indeed populetorum which is highly variable. That was very surprising. I'll add his image.

See you at the LepSoc meeting and thanks for taking the time to unravel this!

I can't find this or your other samples at BOLD. Do you have the Sample IDs? I do see samples submitted by Erik for your area but the dates are wrong. The CNC images at BOLD are very different but they were not barcoded. They are also not public so I can't get further details. It would be nice to know what they are. The dark scales on the wings are different and the color of the scales on the head are different.