I was just reading A Revision of the New World Bistonini (Lepidoptera Geometridae) by
Fredrick H. Rindge, 1975. Yes, I know it is forty-five years old book, but it is the only source that I have found so far that accurately describes in detail the differences between Biston betularia congataria and the rarer Biston betularia contrasta. Link: http://digitallibrary.amnh.org/handle/2246/616
After reading pages 15-19, I was going back through the observations of Biston betularia in North America to see if any of them fit the description of the contrasta subspecies from page 19:
Similar to cognataria, differing mainly as follows: scaling on head, thorax, and abdomen whiter; upper and under surfaces of wings white, with grayish brown, brown and black scales; maculation tending to be reduced.
The moths of this population are poorly represented in collections. Specimens are usually scarce in Utah.
Contrasta is also found in Northeastern parts of Nevada from the map on page 18:
So, should I contact an expert about this? Or a museum to see if they want to add the picture to their collection?