Predacious Diving Beetle - Hydaticus cinctipennis

Moved

… tom murray, 11 January, 2009 - 11:03am

Tim

I just added a close-up of the top of the hind leg. Maybe that will help confirm if it's H. cinctipennis or not. Thanks for all the help again!

… tom murray, 14 April, 2008 - 7:55pm

not sure

Thanks Tom, Unfortunately I'm not sure that does it. I believe we need to see a little further toward the base of the tibia (seems like an "unatural" portion of the hind leg to be visible). Suggest taking a look at Dr. Epler's ref., to see exactly what needs to be seen. He includes a line drawing of the tibia of both species. Even then, I might not be able to tell - it might take a expert like Dr. Epler. He seems to comment on BugGuide every once and a while. You might also consider contacting him.
Tim

… Tim R. Moyer, 14 April, 2008 - 9:25pm

Hydaticus

well my ID track record has a few blemishes on it lately, but here goes: I believe this is definitely Hydaticus, and possibly H. cinctipennis Aube', which appears in Dr. Epler's key from Florida (see Family info page for link).

For the genus, the beetle has all the characteristics mentioned in several keys: medium size, non-emarginate eyes, males with round (not oval) disk on protarsi, outer margin of metasternal wings straight (difficult to see on yours), hind tarsi with golden fringe, and hind outer tibial spur acute.

The species, H. cinctipennis I could only find in Dr. Epler's ref., (not one of the 3 in D&A, but the only other species listed in Nearctica) and no web images. The description matches well (red-brown, not black), but a good close-up of the upper surface of the hind tibia - showing the short spines either parallel to the edge or curving inward basally might let some expert determine this one with certainty.

Hopefully, I at least got it close. But I think I can say with confidence that it's not H. bimarginatus (the "swoop" is different, and the elytra are not black, but red/brown), and therefore another new species for BugGuide :)

… Tim R. Moyer, 13 April, 2008 - 9:26pm