I'm having trouble distinguishing canicularis from linnei- how were you able to determine that my specimen was the former? Thanks in advance!

I wish I had an easy answer, but there are few simple and straight forward answers. However, in some cases it's easier to distinguish than in others.

I always try to consider
1) Locality (Range)
2) Phenotypes per locality
3) Morphology

In this case, the locality coupled with dark coloration, shorter wings, and body build are all indicative of canicularis. Although linnei ranges into Canada, it is generally more gracile, longer wings to body ratio, and typically less variable in color and pattern (as most linnei are well patterned with greens -- NOT to be confused with the fact that some canicularis are also green!).

NOTE: Canicularis is a much more variable species with regards to color and pattern.

Refer here canicularis

for taking the time to reply in so much detail Bill- your generous help is very much-appreciated!