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Photo#161559
Predacious Diving Beetle - Rhantus sericans

Predacious Diving Beetle - Rhantus sericans
Calgary International Airport, Calgary, Alberta, Canada
August 21, 2007
Size: ~ 12 mm
Found dead on the ground at a multi-level parking lot. I think it's in the genus Graphoderus, would like confirmation before I move it there.

Moved
Moved from Rhantus.

looks like i'm wrong...
R. sericans based on Larson's key to species (from his 2001 publication on Neartic Dysticidae)
The single transverse medial band on the pronotum and pale lateral margins of the elytra are diagnostic. This species is reported to be widespread in Alberta.

 
R. sericans
Thanks for the correction. Guide page created

I agree...
with Rhantus binotatus but need to key out first to be certain..From observation, these are quite abundant beetles in Calgary especially during springtime when they emerge from overwintering areas and seek out ponds and other stagnant water bodies (including puddles). Spring is also, I believe, mating season for these beetles. I have quite a few of these in my collection, some with 2 pronotal spots, others with spots fused together like on your specimen.

Moved

I think it´s Rhantus
typical pattern for that genus. The only species as yet represented in bugguide is atypical (at least in European eyes). . .

 
Looks right.
I think you're right! Five species listed for Alberta ... but I have neither the key nor the specimen, so I fear this may be as far as the ID goes :-(

 
R. binotatus?
Rhantus binotatus (Harris) appears to be a likely candidate. See MCZ type here. I believe the black on the pronotum can vary from 2 spots to one connected spot. size should be about 10-12mm. wide distribution includes most of mid and north NAmer.

 
Maybe - I did check MCZ
and noticed R. binotatus. But could there be some other similar-looking species in Alberta? I looked up Rhantus in the (old and likely outdated) Coleoptera Checklist. Seems like the several species have gone through a lot of taxonomic revisions.

 
suggest
I'd suggest "Predaceous Diving Beetles (Coleoptera: Dytiscidae) of the Nearctic Region, with emphasis on the fauna of Canada and Alaska.(1) By D.J. Larson, Y. Alarie, and R.E. Roughley is probably the best single source. I got one through inter-library load. Beyond that, we'd need an expert.

 
Thanks!
Well, I've located a copy in the University of Guelph's library catalogue ... I'm currently back at home for the holiday but I'll know where the book is when I need it. But, I don't have the Rhantus specimen, having discarded it after shooting since it was badly damaged. Now I wish I had not done that!

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