Clubtail? - Arigomphus submedianus

Moved

… Steve Scott, 30 July, 2007 - 9:28pm

Male Jade Clubtail

I would agree with those here that IDed this bug as a male Jade Clubtail (Arigomphus submedianus). Both the humeral stripes and the exact shading of S7-9 can be variable in both Stillwater and Jade Clubtails. IMHO, it is always best to combine those two field marks with a good look at the terminal appendages to separate these two species. Using only one field mark alone is going to get you a correct ID in most cases but certainly not all.

In this case, I think S7-9 show a typical Jade Clubtail pattern, and I would expect S7 to be paler in a Stillwater. As for humeral stripes, it does seem that the dark humeral stripe is a bit wide for a Jade Clubtail. This is hard to discern with these photos, though, and is best left alone b/c the width of the stripe often narrows anteriorly, which we cannot discern. But looking at the terminal appendages, this bug is a Jade Clubtail. If you look closely, you can see the distinctive tapering of the cerci, and the paraprocts would be noticeably longer in Stillwater.

… Nick Block, 30 July, 2007 - 6:35pm

Thanks

Nick. Appreciate the input. I'm moving to species level.

… Steve Scott, 30 July, 2007 - 9:29pm

Arigomphus lentulus

A male Stillwater Clubtail, Arigomphus lentulus, the first one in BugGuide. Nice find!

As always, a shot of the side of the thorax would be nice, but still this species is pretty distinctive, with abdominal segments 7-9 ruddy brown, number 10 light, and of the brown ones, 8 is the darkest. The top of the forepart of the abdomen is especially light in this species.

Arigomphus lentulus has a fairly limited range, but it does include almost all of Illinois.

The scenario with the leaf sounds like egg-laying behavior. I don't know the exact egg-laying details for this species, but many dragonfly females lay eggs by hovering over water, then dipping down into it briefly, repeating for a long time.

Anyhow, a nice find, Steve!

… Stephen Cresswell, 23 July, 2006 - 4:11am

Sure it's not submedianus?

Perhaps these features are secondary to the ones you mentioned, but I do notice green eyes, very narrow shoulder stripes, and the suggestion of epiprocts wider than the cerci (although that is certainly hard to ascertain for sure from the pictures).

… Cliff Bernzweig, 23 July, 2006 - 1:12pm

submedianus

I've seen both. These are the terminalia of the Jade and those shoulder stripes are consistent as well. See the stripes on my specimen here of lentulus (Stillwater).

http://www.hr-rna.com/RNA/Main%20pages/Clubtail%20frame%20page.htm

… Herschel Raney, 23 July, 2006 - 9:03pm

lentulus and submedianus

It is possible it is A. submedianus, and you're right, it may be hard to reach certain ID from the photographs.

Dunkel suggests a key difference between the two is that A. submedianus has the reddish-brown segments equally dark, whereas A. lentulus has a darker segment 8. Under this scenario I would say the photos here suggest A. lentulus. I must admit though, looking at Dunkel's photo of A. submedianus, it looks to me like S8 is darker there.

For what it's worth I have seen A. submedianus, while odeing in Mississippi, but I haven't seen A. lentulus in real life... yet.

… Stephen Cresswell, 23 July, 2006 - 5:50pm

Thanks

Always nice to push us into new territory.

… Steve Scott, 23 July, 2006 - 7:56am