North America’s Rarest Ant, Amblyopone trigonignatha, Found and (OOPS!) Lost

[This breaking news is a guest contribution by myrmecologist Benoit Guenard]

Amblyopone trigonignatha (photos by Benoit Guenard)

The story began with a single specimen in October 1948. A local biologist, D. L. Wray, had been collecting insects in Concord, North Carolina—just east of the middle of nowhere. Wray used a method called Berlese sampling, in which soil animals are “encouraged” out of the soil by use of a hot lamp. This encouragement typically sends them into a funerary jar of waiting ethanol.

In one of the samples Wray took from Concord, he found a few individuals of the ant genus Amblyopone. Ants of the genus Ambylopone are common, particularly in shady habitats across much of North America. There were, at the time, known to be two species. One, Amblyopone oregonensis, in northwestern North America and another, Amblyopone pallipes, nearly everywhere else. These ants appear to eat mostly centipedes and live quiet lives as tiger-like predators underground and under leaves and rocks, hidden from casual observations. At least, there were two species until Wray somehow conveyed his specimens to Bill Brown at Harvard University. Brown looked at the specimens and noted that while one looked just like A. pallipes, the other was unusual. It had a rounder head and an odd, extra tooth. On the basis of that one specimen, an individual dead ant, Brown named it as a new species in 1949, Amblyopone trigonignatha.

During the subsequent 61 years, this new ant species was never heard from again. In fact, rumors began to circulate among the myrmecological cognoscenti that perhaps it wasn’t a separate species at all, but just a weird individual. People began to think that even Bill Brown made mistakes. This ant was a thing of Brown’s imagination.

At least that is what everyone thought until last week.

Last week, Alex Wild (my host here) was trawling through my online photos of the ants of NC and he saw something unusual. He saw an ant that looked like the Amblyopone trigonignatha. In looking at my photos of what I had identified as Amblyopone pallipes, he saw individuals that did not look like A. pallipes. They looked like Brown’s rare ant! Alex sent an excited email to me and copied it to Brian Fisher at the Cal. Academy. Brian sent an email back to us both that, after some expletives, concluded that yes it was A. trigonignatha. And so it was discovered that without knowing it, I had collected A. trigonignatha, sort of.

The individuals that I photographed were found behind my apartment in Cary, North Carolina, just ten minutes from downtown Raleigh, North Carolina. I found them on January 6th, 2008. It was a warm day in January, up to seventy degrees during the day and down to forty degrees at night. The ants moved slow enough that I took the time to photograph them in the wild and then, feeling a great warmth and kindness toward these particular, winter-hardy, ants, lowered them gently back under their rocks. And that was that. I did not collect the ants. I did not study them obsessively (as I have been accused have doing with other species in other times). I had not realized that I had found something so unusual. And so it is that I discovered (without quite knowing it) the second and third individuals of the rarest ant in North America and then let them go, to be free. Oops.

So we are calling all collectors, particularly those living in the Piedmont regions of North Carolina, Georgia and South Carolina, to look for more of what is still North America’s rarest ant, but now, very clearly, appears to be real. It at the very least is now clear that it is exists, though that is all that is clear. Why it was so hard to find, why it is different from other species of the same genus, why it seems to be relatively active during the cool months of the year, well those all remain mysteries. As for me, I can tell you that the most time I have spent inside this week, since hearing from Alex and Brian is to write this post.  So far, no luck with Amblyopone trigonignatha, but Andrea Lucky and I did find two big colonies (69 and 23 individuals) of the lovely ant Proceratium silaceum, covered in mites (Don’t worry, I collected them).

And so that is it for now, I am going back outside.

–Benoit (with a translation and a few jokes from Rob Dunn)

19 thoughts on “North America’s Rarest Ant, Amblyopone trigonignatha, Found and (OOPS!) Lost”

    1. I suppose if we knew where to look we’d have found more of them by now. They’re almost certainly subterranean, though, judging from the collection data and the lack of eyes. So I’d turn stones and look in and under rotting logs, especially in forested habitat.

      As for how to tell trigonignatha from the common pallipes, I don’t know of any obvious field characters. Under the scope the two easiest characters are the shape of the mandibles (more triangular in trigonignatha) and the lack of a strong genal tooth (present in pallipes).

      You can compare all 3 North American species at Antweb.

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  2. James.C. Trager

    Bummer, Benoit. But I am a “conservative” collector, and certainly understand letting these living beings go back to their lives.

    Along these lines, I found a group of A. pallipes workers and larvae, back in July, feeding on an elaterid (!!!) larva, and didn’t have my camera. (!!!) I tried to use another person’s cell phone camera to take a picture, but they turned out unrecgnizable to anyone but me, damn it. (!!!) Thanks for giving me an opportunity to get off my chest a lesser sin than yours, but as an ordained minister in the priesthood of myrmecology (i.e., I have a Ph. D.), I forgive you.

  3. Awesome news! Reminds me of the Tetramorium colony I found that was infested with Anergates… I thought they’d survived the winter, but no…

  4. The label on that holotype reads “Stigmatomma trigonatha”. I find a lot of “Amplyopone (Stigmatomma)” etc. on the web, but haven’t found an explanation.
    Is there an interesting story here?

  5. Dan,

    If you go to the Global Ant Project (GAP) website you will find a link to Bolton’s catalogue and synopsis. In the synopsis, under poneroids, Amblyoponinae, you will find full taxonomic histories of both names.

  6. James.C. Trager

    I wonder if those stouter mandibles help A. trigongnatha grasp beetle larvae with thick cuticles, rather than the more usual, thin-skinned geophilomorph fare of A. pallipes??? (Writer shudders at the thought.)

  7. Gordon Snelling

    Great photos and a wonderful find. However it just goes to show why you should always collect a few specimens no matter how common it seems.

  8. Thanks for sharing the story, or ruefully confessing it as it were. Now I’ll have an excuse to go poke around outside next time I go visit my sister-in-law.

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  11. I’ve done a considerable amount of ant collecting in leaf litter in and around Raleigh, NC, and I always hoped to find this ant, but never did. I sometimes wondered if Wray’s specimen was an anomaly. Now we know it’s really out there. By the way, I knew Dr. Wray, and even asked him about this ant.

    I once collected some A. pallipes in the VA Blue Ridge mountains, and one of the specimens turned out to be a wasp mimic. I think it may have been a bethylid. Alas, it escaped!

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  13. Hmm…I live in the Piedmont region of NC, and I used to study ants in grad school. I guess I should start turning over rocks again…

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