Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Clickable Guide
Moths Butterflies Flies Caterpillars Flies Dragonflies Flies Mantids Cockroaches Bees and Wasps Walkingsticks Earwigs Ants Termites Hoppers and Kin Hoppers and Kin Beetles True Bugs Fleas Grasshoppers and Kin Ticks Spiders Scorpions Centipedes Millipedes

Fall Fund Drive

TaxonomyBrowseInfoImagesLinksBooksData
Photo#114394
elytral depressions ground beetle - Pterostichus adstrictus

elytral depressions ground beetle - Pterostichus adstrictus
Jefferson Notch area, Coos County, New Hampshire, USA
May 27, 2007
Size: about 11 mm
Found under very loose bark of spruce log. The elytral depressions were a welcomed sight since they seemed like a distinctive-enough feature to permit ID to species level. Note that the depressions alternate between the second and third entire stria from the elytral suture.

Images of this individual: tag all
elytral depressions ground beetle - Pterostichus adstrictus elytral depressions ground beetle - Pterostichus adstrictus elytral depressions ground beetle - Pterostichus adstrictus elytral depressions ground beetle - Pterostichus adstrictus

Moved
Moved from Pterostichus.

Moved
Moved from Ground Beetles.

Our fauna are close in part
Seems to be the nearctic sibling of European Pterostichus oblongopunctatus - a common forest species, found under same circumstances.

 
There are 24 Pterostichus in New Hampshire
according to Don Chandler's checklist. These include P. adst*rictus, which looks similar to this one.

 
In Province of Québec (and p
In Province of Québec (and probably also in New Hampshire), they are also the species P. pennsylvanicus that is very similar to P. adstrictus and both are really easy to confuse sometime. But on this guy, the baso-lateral ponctuation of the pronotum is easy to see, and it is probably effectivly P. adstrictus.

 
Thank you, Pierre-Marc.
I'm adding a better dorsal view of the pronotum as well as some other views.

 
Pterostichus adstrictus vs pensylvanicus
By far the best account to distinguish Pterostichus adstrictus vs pensylvanicus on external characters is the article "Number of Clip Setae on Protibia as a Diagnostic Character Between..." - Y.Bousquet in The Coleopterists Bulletin 40(4):353-354, 1986. I find external traits of decreasing reliability to be 1: number of clip setae, 2: ratio of elytra/pronotum lengths, 3: curvature of lateral pronotal margin, 4: degree of convexity lateral to posterolateral foveae of pronotum. Most other external differences cited in Lindroth (1961-1969) are very unreliable. Traits for P. adstrictus vs pensylanicus are respectively 1: 3 vs 2, 2: 2.35 - 2.70 vs 2.15 - 2.35, 3: straighter toward hind angles and widest clearly before middle vs evenly rounded toward hind angles and widest near middle, 4: flatter vs more convex and continuous with convexity of pronotal disc.

 
Thanks, Peter.
Based on pronotum:elytra ratio this has to be P. adstrictus then.

Comment viewing options
Select your preferred way to display the comments and click 'Save settings' to activate your changes.