Plionoma suturalis in Oklahoma—a new state record!

When I returned from my vacation/insect collecting trip to western Oklahoma two weeks ago, most people upon learning where I went responded with a funny look that said, “Why would you want to go to Oklahoma?” Even entomologists familiar with my inclination for beetles merely assumed I went there to collect tiger beetles and were surprised to learn that, for this trip, I was actually targeting jewel beetles (family Buprestidae) and longhorned beetles (family Cerambycidae). Jewel beetles and longhorned beetles, of course, are largely associated with dead wood, and western Oklahoma is smack dab in the middle of the Great Plains. However, this does not mean that there are no trees in the area, or that whatever trees do exist are merely western examples of pedestrian eastern species with a depauperate beetle fauna. In fact, I came to this area precisely because previous visits had seemed to indicate high potential for interesting species of woodboring beetles. On my September 2011 visit, passing through on my way back from Colorado, I found several individuals of the unusual fall-active Acmaeodera macra (representing a northern range extension), and during last year’s fall visit I found a single Chrysobothris octocola adult on a dead mesquite (Prosopis glandulosa) branch—a northeastern range extension and new state record for Oklahoma! Interesting records for other species of beetles over the past few years also supported the idea that western Oklahoma was understudied and held the promise of more interesting new records for anyone willing to spend time in the area.

Plionoma suturalis (male) | Gloss Mountains, Major Co., Oklahoma

Plionoma suturalis (male) on mesquite (Prosopis glandulosa) | Gloss Mountains, Major Co., Oklahoma

Nearly all of these interesting records have been found in the Gloss Mountains, a fascinating system of gypsum capped, red clay mesas in Major Co. I now regard the Gloss Mountains State Park as my “portal” to northwestern Oklahoma and can’t imagine traveling to or through the area without stopping and spending time knocking around this fascinating, brick-red landscape. Such was the case during this year’s trip, and while I had decided to spend at least the first field day in and around the State Park, the collecting was so good that I stayed for a second day and returned for a third later in the week. The beetle shown in these photos is part (and only part) of the reason why. Arriving in the morning of the first day in the field, I headed straight for the mesquite tree on which I had found the C. octocola adult last fall. It’s a common species in the southwestern U.S. that normally wouldn’t warrant any special attention, but since the Oklahoma record was based on a single specimen I wanted to see if I could find additional individuals to confirm that the species was actually established in the area and that last year’s record wasn’t just a one-off. I whacked a dead branch, and onto my beating sheet fell a C. octocola adult! I whacked another dead branch, and off fell another adult! As it was, I would find the species as abundantly here, in strict association with mesquite, as I have seen it at other locations further to the southwest. Soon after collecting the first few C. octocola adults, however, I whacked a live branch on the same mesquite tree, and off fell two large, colorful longhorned beetles that I recognized instantly as representing the species Plionoma suturalis.

Plionoma suturalis (female) | Gloss Mountains, Major Co., Oklahoma

Plionoma suturalis (female) on mesquite flowers | Gloss Mountains, Major Co., Oklahoma

Plionoma suturalis belongs to the great tribe Trachyderini. Beetles in this tribe are known for the bright colors, attraction to flowers, and diurnal (day-active) tendencies, and while we have a few species in the eastern U.S. they are far more diverse in the southwestern states. Plionoma suturalis and another U.S. species (P. rubens) are known to occur from Texas west to California and south into northern Mexico, but I immediately had the feeling that finding this species in Oklahoma was a significant record. The beetles were abundant on the mesquite trees that lined the parking lot and dotted to landscape below the main mesa, with many observed feeding on the flowers (the trees were in full bloom) and numerous mating pairs also observed. Considering its abundance at the site and possible significance of the record, I collected several dozen specimens to serve as vouchers (not to mention I had only collected a handful of specimens in all of my previous years of collecting). Checking my database later that evening (I never leave home without my computer!) confirmed my suspicions—Oklahoma was not only a new state record, but a significant northeastern range extension. In fact, the closest previous record was by Lingafelter & Horner (1993), who recorded eight specimens from Wichita Co., Texas—just over 200 miles to the south! Further, the Wichita Co. specimens were all collected in 1956, and subsequent collecting had yielded no additional specimens, leading the authors to consider the status of this species in north-central Texas as doubtful.

The female feeds on flowers of mesquite (Prosopis glandulosa)

Large number of individuals were seen feeding on mesquite flowers.

Plionoma suturalis is one of only a handful of North American longhorned beetle species in which the adults exhibit bimodal seasonal activity, with adults appearing during the spring months, disappearing during the summer, and reappearing in the fall (see  for a previous example from Missouri) (Linsley 1962). In the Lower Rio Grande Valley of south Texas (where the activity of many species of longhorned beetles and other insects is distinctly bimodal to coincide with moderate temperatures and increased precipitation during spring and fall), this species has been found on fresh-cut mesquite and huisache (Acacia farnesiana) in the fall months and on the blossoms of fabaceous trees during spring and early summer (Hovore et al. 1987).


Hovore, F. T., R. L. Penrose & R. W. Neck. 1987. The Cerambycidae or longhorned beetles of Southern Texas: a faunal survey. Proceedings of the California Academy of Science 44(13):283–334, 20 figs.

Lingafelter, S. W. & N. V. Horner. 1993. The Cerambycidae of north-central Texas. The Coleopterists Bulletin 47(2):159–191, 7 figs.

Linsley, E. G. 1962. The Cerambycidae of North America. Part III. Taxonomy and classification of the subfamily Cerambycinae, tribes Opsimini through Megaderini. University of California Publicatons in Entomology 20:1–188, 56 figs.

Copyright © Ted C. MacRae 2013

11 thoughts on “Plionoma suturalis in Oklahoma—a new state record!

  1. Wow! Interesting and exciting about the new record and finding so many. Because I’m unfamiliar with this side if things, do you get a mention somewhere when there is a new record? And now that you’ve got proof they are in abundance?

    • A “new record” just means that it hasn’t been documented in the scientific literature. I’ve been documenting such records for Buprestidae and Cerambycidae over the years in my own papers and will add this record to the next paper I put together. It’s not that big of a deal to most people, but to us taxonomic sorts documenting range extensions and previously unknown elements of their biology or natural history is exciting stuff!

  2. I was surprised (i.e., great timing) to see your recent article with photos of the longhorn beetle Plionoma suturalis, since I had just captured numerous specimens of this species and also Aethecerinus latecinctus on the flowers of a single mesquite tree, west of Van Horn, Hudspeth County, Texas on June 2 (2013). Both species were remarkably abundant, some flying in while others were feeding. Also present were a number of other species of beetles, including two kinds of Acmaeodera — one 12-mm long with two rows of five yellow markings, and a 6-mm species with two rows of 2-4 markings. Perhaps you will identify these for me if I forward some photos. Thanks, Bob Wrigley

    • Sounds like you had a good trip also. I’ve only collected a single Aethecerinus latecinctus—as you know timing is everything with so many of these things (especially out west).

      Feel free to send pics of the Acmaeodera, but the bigger one sounds like A. gibbula and the smaller might actually be an Acmaeoderopsis.

  3. Wow, that’s a beautiful beetle! I’m glad someone recognizes the entomological potential of Oklahoma 🙂

    This year, thanks to all the tornados we’ve had, there are plenty of dead trees. I’ve probably seen more wood boring beetles this year than in all the rest of my time in Oklahoma.

    • I didn’t see any recent tornado damage in the areas I visited. My impression is that several years of drought has caused a lot of tree stress and branch dieback and that timely rains before my visit triggered good emergence. Sometimes you just get lucky.

  4. I found a Plinthocoelium suaveolens – beetle today in Davis, Oklahoma. Kept him for awhile – wanted to see if he was a good bug or a bad bug. Anyway – couldn’t find any info on him, so I let him go. Hope he doesn’t destroy any of my trees or plants!

    • Lucky you! Plinthocoelium suaveolens feeds only on bumelia trees, a native plant found in glades and prairies. Adults feed on the flowers, while the grubs live inside the roots. I consider them to be the most beautiful of all North American longhorned beetles, and you certainly are among the lucky few to have gotten the chance to see one of these beautiful beetles. I wrote a post on my quest to photograph the adult, maybe you will be interested to read it:


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