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ground beetle - Polyderis laeva

ground beetle - Polyderis laeva
Lynnfield, Essex County, Massachusetts, USA
April 1, 2007
Size: 1.5mm

Polyderis laevis
It sure fits the description, especially the small size, and it looks just like the picture. Thanks Tim!

Trechinae, Bembidiini, Elaphropus?
. . . can´t be much else, being so small.

What do you think about Polyderis? I flipped through Downie and Arnett for the Bembidiini tribe, and while size is not the best criteria, the smallest 2 Elaphropus listed are 1.9mm-2.5mm, and they are both described as dark brown.
Conversly, Polyderis laevis (only NAmer species) is described as "1.2-1.5mm, piceous to brown, elytra truncate at apex, striae faint, smooth, only sutural one impressed, #8 barely present at apex", and "Our smallest carabid"! And it's listed occurring in Mass and throughout Eastern NAmerica (specifically including Mass). Once again the Canada Carabid site provides a photo here

what do you think?

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