which apparently was regularly confused with pygmaea by taxonomists for so long that a paper was finally published to straighten them out (see PDF doc).

The PDF doc says of pygmaea: "forewing is dark brown with some lighter areas... there is practically no bluish-gray as in P. abrostolella."

And it says of abrostolella: "distinguished from pygmaea by its blue-gray appearance. Whereas P. pygmaea is dark brown, P. abrostolella is a bluish gray species that varies from pale to dark gray. The black markings are thinner and finer.
This species, misidentified as Paectes pygmaea, was illustrated by Holland (1903) plate 29 (2)."
The Holland plate is here but the image is too small to be of much value (except to show that the hindwing is not completely black, as it would be in pygmaea).

On page 6 of the PDF doc is a map showing records of both species in the northwestern Arkansas area, so I'm afraid distribution won't help to separate the two in this case.

There's better photos on the web of both species at MPG (1, 2), and abrostolella alone at CBIF. One thing I noticed, but don't know how reliable it is: the two lines that make up the double PM line are about equal weight in pygmaea, whereas the outer line looks heavier in abrostolella.

I actually consulted several people on this one, and got conflicting reports. One thing I didn't take into consideration, was the size estimate method - I'm so used to WS sizes that I was thinking 15mm with margin of error of maybe 2 to 3mm, puts the WS size in pygmaea country. But if the size estimate is of the resting posture, that would put the WS size at approximately 29 to 32mm - firmly in abrostolella territory. So you're probably right. I was told that abrostolella typically has more (stronger) black markings in the subapical area (particularly in regard to the 3 subapical dashes), but I don't know if that's reliable - it appears it may not be.

What's even more frustrating is I have one in my collection that was ID'd as pygmaea, yet its FW fits the abrostolella description to a T, while the size (est WS 22mm) and black HW indicate pygmaea. It definitely seems that even the experts are still struggling with these Paectes.

I haven't reviewed the pdf file yet, so I say move as you see fit. Thanks for the help and for finding that paper.

Cheers!

We certainly have enough sweetgum around here to support a large population.