No updates yet. I extracted DNA from this and a number of Scaphinotus (Nomaretus) and S. (Maronetus) but haven't sent it off for sequencing yet.

We had a MS student run 10 pitfall traps and collect 10 leaf litter samples every two weeks for a year at the same locality and didn't recollect the species.

as a new Wisconsin record. Michael, there I attributed my revision from "S. bilobus" to "S. fissicollis" based in large part on the typical male specimen fr AR that you kindly donated to my synoptic set. Regarding your specimen imaged on this page, surely the discussion of Nomaretus vs Maronetus (and therefore possible "incompletus") can be resolved by inspection of the numbers of setae at labrum base and on labial palpomere #2 per key in American Beetles 2001:43.

Your specimen appears to be a Maronetus and the known species are divided between three groups: imperfectus, hubbardi and debilis (which includes incompetus which you mentioned).

To paraphase Barr:

The hubbardi group have rows of discal punctures on the elytra, (can be difficult to see).

The debilis group are larger, 9-12mm, with beaded prontal margins, more deeply impressed striae on the elytra and sparse but distinct punctures on the epipleura.

The imperfectus group are small, (7-9mm) with wholly or partially obliterated marginal beads on the pronotum.

If your specimen is a Maronetus it would not only be a new species for AR but also a new subgenus for that area.

Back to incompletus, I just caught three in KY. Not bad considering that between 1895 and 2009 only 8 known specimens were collected, (although I caught another 11 in 2012).

I think this is subgenus Maronetus rather than Nomaretus. Looks like Scaphinotus (Maronetus) imperfectus but don't know if that species is in Arkansas.

are easily separated under microscopy according to the key in American Beetles Vol 1 (2001) p43. Image details are not adequate to apply to that key. I do note that the published western limit for M. imperfectus is the stretch OH-WV-VA-NC and therefore not close to AR. In fact, I don't see any Maronetus given AR status in the catalogue by Bousquet & Larochelle 1993.

I have no idea how to distinguish the two subgenera and have never collected either (despite all my efforts to find bilobus up here in maine). I am working on a checklist of NE scaphinotus and just recently went through the Cychrini cabinets at the USNM. They had a few imperfectus (i think this bug is rare or at least cryptic) and I had some deja vu and then remembered this semi-squashed bugguide specimen. If you click on the Harvard-MCZ link above and hit the "compare" icon, I think the imperfectus is by far the best match (superficialy at least - actually I think it's the only one that is even close).

when comparing to MCZ type specimen. Thank you for pointing this out. I feel it would take a leap of faith to say they are conspecific based just on these images. It would be great to examine this specimen against published keys. There is the exciting chance that it is indeed Maronetus imperfectus and therefore the discovery of a significant range extension to the west.

Tried to work through the American Beetles key. Antennae 3-11 are pubescent, which goes to couplet 8.
The labrum has 2 setae at the base and 2 setae distally. This doesn't seem fit with the key, which asks if there are 2 or 4 setae at the base of the labrum, not 2 or 4 setae overall. The 2nd labial palp has 4 setae, two distally and two about midlength, which would indicate Nomaretus and not Maronetus, but I'm not sure since I can't interpret the labral setae character asked by the key.

would exclude Maronetus and include Nomaretus. Labrum base (deeply emarginated) should show 4 distinct setae to clinch Nomaretus. Perhaps two were broken off at their bases?

I have Tatiana Gidaspow's key from 1973 Cychrus revision (just google and can find paper on line). According to that key, Maronetus has 2 setae at the base of the labrum (YES - and i think that photo is very clear), 10 at most, usually fewer elytral striae (YES - also very clear in the photos), BUT only 2 setae on penultimate segment of labial palps (NO - are you sure didn't photograph maxillary palp?).

On the other hand Nomaretus and Pseudonomaretus have 4 setae at the base of the labrum (NO), always more than 10 elytral striae (NO), BUT more the 2 on setae penultimate segmentlabial palps (YES).

????? wasn't there a song "two out of three ain't bad"????? Thus, i'm still leaning towards Maronetus.

Or, I propose a new species and (more importantly) genus: Pseudomaronetus skvarlai!! :-)

It would not surprise me if Maronetus turned up in Arkansas. Sphaeroderus was recently discovered there, on the west side of the Mississippi, and they seem to be a new species.

I discovered a giant Nomaretus population in Arkansas a few years ago that I think is a new species. So there are interesting things happening in Arkansas.

I thought about S. incompletus for the specimen pictured but the pronotum is more like imperfectus.

I could send a couple Brennus in an exchange if you'd like! Feel free to send me an email if so. Regards

The lab I'm in is working on endemic species in Arkansas; related to that, we're working on a publication for range expansions and new state records of wider ranging species.
I'm very interested in getting an ID on this, but it's the only specimen of this species we have right now. I'd be willing to send it to someone to confirm the ID. If it's a new species I'd ask that the holotype be deposited in the NMNH and if it's described that the specimen be returned to us for deposition in the University of Arkansas Arthropod Museum.

Barr was the expert on these eastern Scaphinotus and unfortunately he recently passed away. I tried to catch some of this mysterious beetle at Wedington Lake this year but missed. I will probably try again next year.
Barr seemed to be of the opinion that Scaphinotus parisiana, (considered my most to be an Arkansas endemic) ranged into central Missouri, southern Illinois. I have a few specimens of "unicolor" from southern Indiana that look very much like parisiana. Thought I'd mention it.