Loxandrus sp? - Pterostichus obesulus

Pterostichus obesulus

The subgenus Gastrosticta isn't treated by Ciegler, because no species of that group are known from SC. I recently refreshed my memory on these after surprisingly finding one near Abbeville SC. They aren't very commonly collected, and the southern species seem to hang out in swampy areas at cold times of year.
This species is unique in having the pronotum with those widely flattened edges at the base, and is apparently very rare. This is a fantastic addition to Bugguide! I have a PDF of Bousquet's revision of the subgenus, if you're interested. It has a nice detailed drawing of this species.
Moved from Pterostichitae.

… Curt Harden, 20 January, 2020 - 11:00pm

Pterostichus "obesulus" aptly refers to the plump pronotum.

Kudos to Curt for his image-based detective work and persistence with this rare one. Curt, please share the image & record of your South Carolina find so it can be added to the Caraboidea Registry.

… Peter W. Messer, 21 January, 2020 - 9:09am

I will, once I get a good photo

The SC one is a single female, so I'm not comfortable putting a species name on it. I'll be going back to the spot a lot, so a male will turn up someday I hope.

… Curt Harden, 21 January, 2020 - 9:49am

"Ground Beetles active during cold months"

would be a great publishable project presented more or less as an annotated checklist. The list would include Pterostichus obesulus, Hartonymus hoodi (tenerals active in October), and at least a few more species I think. Please pass on the idea.

… Peter W. Messer, 21 January, 2020 - 10:07am

That would be great

Plenty of carabids seem to wake up and get active on warm days in winter, but it would be useful to compile information on the species that seem to actually be primarily active in colder months.

… Curt Harden, 21 January, 2020 - 10:38am

Moved, I don't think this is Loxandrus

Moved from Loxandrus.

… Curt Harden, 26 December, 2019 - 8:49pm

More than image matching

is needed to be confident that this one is Loxandrus and not, say, Pterostichus. Typical Loxandrus shows elytra with shiny iridescent reflections not always captured by photography. Ciegler (2000) gives illustrated keys for separating related genera and the species of Loxandrus in South Carolina. Bruce, if you want to get serious about identifying tribes and genera, that book is a good place to start as it covers a good portion of the Florida carabid fauna. The scientific value of a BugGuide photograph increases when the submitter confidently observes and reports distinguishing characters not well captured by the image.

… Peter W. Messer, 22 January, 2011 - 11:41pm

Loxandrus

For Mr. Messer: ref (1):Starting from pg 6; 1,3,4,27,36,44,
49,50,51,53,54,55,56,59,61,62,65,78,79,80;front tarsus of male
asymmetric = Loxandrus > pg 57; 1,10,12,15,16,19=L. cincinnati.
There are two setegerous punctures above the eyes and the anterior
margin of the clypeus is straight. Pterostichus, according to the
literature are generally >10.5mm. What else can this poorly trained,
amateur submitter provide for you????

… Bruce Getty, 23 January, 2011 - 2:23pm

Excellent trip through Ciegler's key to Loxandrus.

The main points (not in your initial post) are that you saw the elytra iridescent and the male protarsi asymmetric. The imaged pronotum suggest to me well-rounded hind angles, so couplet 12 would go to 13, then 14, L. uniformis. Body size and punctate hind angles appear consistent with that species. However, L. uniformis (closest AL, SC) is not known in FL so you might have another species. For full North American key see Robert T. Allen (1972)- Revision of genus Loxandrus. Hope this helps.

Tips in reading Ciegler: "shiny" is often code for obsolete surface microscuplture vs "dull" which imples distinct surface microsculpture. The differences are best seen under high power.

… Peter W. Messer, 23 January, 2011 - 3:47pm

wow....

… James E. Garrison, 25 January, 2011 - 12:14am