Synonyms and other taxonomic changes
Syngrapha cryptica Eichlin & Cunningham, 1978
cannot be reliably separated using DNA barcoding, PLoS ONE 12(6): e0178548; Supplementary Table S8 (1)
. Examiantion of genitalia is usually required.
"Syngrapha rectangula is easy to identify in most of its range because of the large amount of silvery shading - except near the West Coast where it has a dark form that looks a lot like alias and often needs to be dissected to be sure.
In the Smithsonian there were about 150 S rectangula from the Maritime Provinces and Maine and they were sorted into the typical silvery form and a darker form (with much less silver, especially near the wing base. On dissection, it turned out that the "dark form" were all S cryptica... Syngrapha cryptica was described exclusively from Michigan and Wisconsin - highly disjunct from the Maritime populations. We have since found it in Ontario and Quebec. The East Coast populations of cryptica look a lot like rectangula, but there is less silver, and often there is a rounded dark patch in the terminal area about 1/3 from the top. The Ontario and Great Lakes form of cryptica looks very different, but the genitalia are the same, but maybe they're different species - the coastal form has not been barcoded, but it looks like that wouldn't help anyways, so best to stick to the genitalia and call them geographic forms. The inland form has brown shades in the forewing and the silvery areas, especially in the basal area, have a definite greenish tone, so they are relatively easy to pick out - especially after you've seen a real one in the flesh..." - C. Schmidt & D. Lafonataine (pers. comm., 03/5/2018)
Lafontaine, J.D. & R.W. Poole, 1991. The Moths of America North of Mexico, Fascicle 25.1: p. 115; pl. 3.37-38