Need help with geometrids: Orthofidonia sp., Cormierville, Kent Co., 9 June 2018

There are three species of geometrids in the genus Orthofidonia known from New Brunswick. Judging by the number of NB dots at MPG and photos at BugGuide the commonest appears to be Yellow-veined Geometer Orthofidonia flavivenata #6430. O. tinctaria #6428 has quite a few NB dots at MPG but only three BG images for all of North America while O. exonata #6429 has several NB dots at MPG but only one image for all of North America at BG. There are no photos of any of the three species here at BNB. 

I don't believe I've ever had one at the lights but on the evening of June 9th I photographed two individuals at the lights which I think may be in the genus. One is quite worn but the other is in good shape. I don't see any indication of yellow venation which most Yellow-veined Geometers seem to show. There are so few live images of the other two species that I really don't know what these are but I'm leaning more toward O tinctaria (known as Marbled Wave at BugGuide).

I'd really appreciate guidance with these if anyone has any thoughts.

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Stu, for what it's worth, after viewing images of 6428 and 6429, I would agree with your take as to 6428.

Hope Tony sees this post.

Thanks, Jo. Also have an Iridopsis from the same evening that I'm not sure about. I'll post it tomorrow.

6428 and 6429 can be definitively separated by genitalia; long thought to be just 1 species.

However, males can be separated if one able to measure the antennae: in exornata the length of the antennal setae are much longer than the width of the main antennaal shaft; in tinctaria about equal to shaft width.

Thus, male antennae are 'hairier looking' in exornata.

Thanks very much, Tony. Next time I'll try for an extreme close-up of antennae.

While I have your attention could you offer any advice on this Iridopsis - vellivolata, humaria or just larvaria? Or none of the above.....  9 June 2018 Cormierville.

not humaria, it has a black band across abdominal segment 1 that lines up with the wing band.

ephyraria is grey, has  a conspicuous grey patch on apex of underside of FW

yours is vellivolata, no such patch.

Duly noted. Thanks very much, Tony.

This post is informative!! 

The more new ones I get, the longer it seems to take to ID them!  Lots of tricky ones.

Happy to see you finally mothing Stuart!!  

Thanks, Nancy. I just wish I had a few more subjects to work with. Seems it is always too cold, wet or windy (or all of the above) in the evenings here. I think it was Jo who mentioned that it had been hot and humid either yesterday or the day before and I had to groan. I think both days topped out in the upper teens here. Of course today is a washout with all the rain and a mid-day temperature of 8C. Maybe tomorrow........   :)

It was slightly over 28 C here yesterday, Stu, much lower today with BIG rain as well. I didn't put the trap out last night but plan to do so tonight.


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