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Hydrophilidae ? - Hydrochara obtusata

Hydrophilidae ? - Hydrochara obtusata
Groton, Middlesex County, Massachusetts, USA
April 21, 2007
Size: 16mm

Images of this individual: tag all
Hydrophilidae ? - Hydrochara obtusata Hydrophilidae ? - Hydrochara obtusata Hydrophilidae ? - Hydrochara obtusata

Thanks Tim
You've come through nicely again! Another species identified.

The small spine must be at an angle that doesn't show up in this photo. It does look like the others on the guide page. Thanks for another id Patrick!

Spiney thingy
I believe it is there, but doesn't protrude beyond the rear coxae. If I am reading the key correctly, it protrudes in Hydrobiomorpha and does not protrude in Hydrochara. Mine down in NC have brownish underneath--yours are blackish--probably different species.

Crossing my fingers as always...., since you know how much formal training in entomology I have.

dilated spiney thingy
the sternal keel (spiney thingy) appears to be dilated in the metasternal portion(between middle and hind legs), thus being different than Patrick's previous posts. And yes, the ventral coloration and legs are much darker. If we could see the tip of the last segment of maxillary palpi, to see if they are darkened or not, then from the Downie and Arnett key we'd probably have a species determination.

I'm not sure, but I think the middle picture shows a light colored palpi tip just barely sticking out.

ok (I wasn't sure what exactly was sticking out), then this would seem to be Hydrochara obtusata (Say), at least as far as I can tell from Downie and Arnett. 12-17mm. Distro includes northeast and northcentral NAmer.

formal training in entomology
Other than the professional entomologists that contribute to bugguide, you're right at the top of the list as far as I'm concerned.

Compare this one
Looks to be the same, or very similar to a Hydrochara:

Moved from Beetles.

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