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Photo#265536
Dytiscid - Acilius semisulcatus

Dytiscid - Acilius semisulcatus
Groton, Middlesex County, Massachusetts, USA
April 12, 2009
Size: 12.4mm
This might be Acilius mediatus, but it just looks a little different to me.

Images of this individual: tag all
Dytiscid - Acilius semisulcatus Dytiscid - Acilius semisulcatus Dytiscid - Acilius semisulcatus Dytiscid - Acilius semisulcatus

Moved
Moved from Acilius mediatus.
Don Chandler identified a specimen I gave him. The date on my label was off by a few days, but this has to be it, since I have no other photographs of an Acilius near this date.

Moved

Yes, female A. mediatus
Another species that might be similar would be A. fraternus- in both species, females are non-sulcate (with no elytral ridges) and the hind legs are dark in colour (dark red to black). However A. fraternus is larger (min. size= 13 mm) and may not/rarely occur in your area (northern limits- NY)

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