Answer to the Monday Mystery: An Unexpected Tetramorium

Tetramorium sp. (aculeatum-group) – Kibale forest, Uganda

When I first saw the trail of leggy brown myrmicines splayed along a tree trunk, I thought the ants must be Pheidole. After all, they moved like predatory Pheidole I know from South American forests. But their ranks contained none of the telltale big-headed soldiers, and when I viewed the shape of the mesosoma in my photos I knew the identification had to be something else. But what?

Marek gets 8 points for his correct answer, a species in the Tetramorium aculeatum group. Additional points go to Guillaume D. (2 pts) for being first to the subfamily, and to Josh King (1 pt) for making me laugh. Thanks also to Brian Taylor and to Pangapaco for additional information.

The trouble with the mystery ants is that we Americans are accustomed to Tetramorium as drab, chunky, monolithic little insects. Most of our species are small, blocky things imported accidentally from the old world. Here’s the ubiquitous pavement ant, for example:

Tetramorium sp. nr. caespitum (Illinois)

North America’s most extravagant Tetramorium is like a slightly longer, slightly lighter pavement ant:

Tetramorium bicarinatum (Florida)

Yet Africa is different.

There, for reasons we can only guess, Tetramorium flowers into an astounding array of shapes and hues. Consider:

Tetramorium pulcherrimum (Kibale forest, Africa)
Tetramorium sericeiventre (South Africa)
Tetramorium sp. (Kibale forest, Africa)

For more, see Antweb’s Tetramorium of Africa.

Visiting other regions with open eyes forces us to challenge what we think we know of particular lineages. Evolutionary processes have played out differently among the continents, and Africa has indeed been kind to Tetramorium.

Oh, and our monthly mystery winner, with 10 points from early October, is Warren. Contact me for your loot, Warren!

5 thoughts on “Answer to the Monday Mystery: An Unexpected Tetramorium”

    1. “Lateral parts of clypeus forming a raised, sharp edged rim in front of antennal insertions; sting with a lamellate appendage found apicodorsally that projects at an angle to the long axis of the sting shaft” (source)

      Basically, Tetramorium all share an unusual form to the antennal insertions and a peculiar “flag” on the stinger.

  1. James C. Trager

    Seen through these lovely images, this genus becomes really interesting (notwithstanding its myrmicinity 🙂 ).

  2. Sorry to have come across this so late (my computer has been suffering some terrible headaches recently).
    There is also a good apomorphy in the males that is diagnostic of Tetramorium: the second segment of the antennal funiculus is an elongate fusion segment.

  3. Interesting! Strongylognathus, Rhoptromyrmex and Teleutomyrmex males also seem to have this elongate segment, but apparently not Anergates?

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