An Acrobat Ant’s Acrobatics

If you’ve ever wondered why Crematogaster acrobat ants have such an odd shape, take a look at this:

Crematogaster & Pheidole, Kibale Forest, Uganda

In Uganda’s Kibale Forest last summer, I smeared a bit of cookie cream along a rock as ant bait. A pleasingly yellow Crematogaster soon arrived to feed. All was well until a second species, in the big-headed ant genus Pheidole, attempted to sneak a taste.

Crematogaster & Pheidole, Kibale Forest, Uganda

Instantly, the acrobat ant swung her agile abdomen forward – while still feeding (!) – and warded off her competition with a dab of venom. Like many myrmicines, Crematogaster has a stinger, but the structure has evolved from a piercing weapon to a soft, flexible, brush. The unique shape of the acrobat ant abdomen allows these ants to deploy their chemical weaponry in nearly any direction.

Friday Beetle Blogging: Beauty and Youth?

Rove beetle larvae – Kibale forest, Uganda

Most of us think of beetles as heavily armored and often colorful tank-like animals. But they aren’t born that way. Like all insects with complete metamorphosis, beetles start as grublike larvae bearing little resemblance to the adults. I photographed these two immature rove beetles while searching for ants in a rotting log.

photo details:
Canon MP-E  65mm 1-5x macro lens on a Canon EOS 7D
ISO 200, f/13, 1/200 sec
diffuse twin flash

The mystery of the ant’s cadaver

A grisly scene in Kibale forest, Uganda:

I found this long-dead cadaver stuck to a tree trunk at about waist height. The body must have been there for months or even years, judging from the moss growing across the cuticle.

Why is this puzzling? Rainforests are intensely competitive environments, and free protein does not stick around for long. So why would a perfectly good ant go uneaten?

My suspicion is fungus. If the ant was killed by a Cordyceps-type organism, the tasty innards would long have been consumed by the parasite. Still, that’s just a guess.

In life, the ant (Polyrhachis militaris) would have been covered in golden hairs.

The first live photographs of Terataner?

Continuing our series of First-Ever-Photographs, after some research I suspect I have taken the first live images of the African tree-dwelling ant Terataner:

Terataner elegans (Kibale Forest, Uganda)

If you know of other photographs, speak up! I’ve been unable to find any online, nor in the scant technical literature on this genus.

The crew at Ant Course 2012 collected a twig nest of Terataner elegans along the roadside entrance to the Makerere University Field Station in Uganda, letting me borrow it for a few photographs before the ants were pickled for Cal Academy’s research collections. I had never seen live Terataner before. They reminded me a great deal of the related Australian genus Podomyrma, as both are muscular arboreal insects.

Terataner elegans (Kibale Forest, Uganda)

That images of these ants are exceedingly rare is not some boast of my photographic prowess; rather, it’s an observation on the paucity of African ant research relative to just about anywhere else in the world. Africa holds great promise for discovery.

Terataner elegans (Kibale Forest, Uganda)

The Uganda Photographs

The dreaded Siafu: Dorylus sp. soldiers guard a foraging trail.

If you’ve been following Myrmecos, you might know I was lucky to instruct this summer’s Ant Course in Uganda. Unsurprisingly, it was epic. And I’ve got the photos to prove it:

Photographs from Ant Course/Uganda

During the 10-day course I took 5,280 exposures. After culling and processing, as of this afternoon I have uploaded 202 of the best. This is a 4% keep rate, very much in line with the 3% baseline from Australia and Brazil earlier this year. Some of these photos you may have seen in my various posts over the past couple months, but most are shiny, new, and unblogged. I hope you enjoy them.

The second-ever live photographs of “Disco Ants”: Discothyrea mixta & Discothyrea sp.

Myrmecologists, being only human (most of the time), have an irrational fondness for the proceratiine genus Discothyrea. Why? Have a look, and try not be overwhelmed by the cuteness of a pudgy muppet ant:

Discothyrea sp. (Kibale Forest, Uganda)

Discothyrea occurs in tropical climates around the globe, but as they are extremely small (1-2mm long), and as they live ensconced in soil and leaf litter, they are rarely seen. These little ants are never abundant, most likely because they are specialized predators on the eggs of another group of predators: spiders. Still, preserved “Discos” turn up in litter samples occasionally, and just about everyone who works on ants knows about them.

Discothyrea sp. (Kibale Forest, Uganda)
Discothyrea mixta, nest with prey eggs mixed in among their own brood. (Kibale forest, Uganda).

I had not seen Discothyrea alive until this summer. At Ant Course in Uganda we encountered at least two species; the first, pictured at the top on white, is typically reduced in features, showing few easy taxonomic characters. Given the group’s dire need of taxonomic revision I did not feel comfortable putting a name to it. The second, D. mixta, belongs to a distinct subgroup with larger eyes and a distinctly raised frontal lobe. Jack Longino found the nest pictured here and brought it to the lab for observation.

Discothyrea mixta transporting a prey egg with a first-instar ant larva (Kibale forest, Uganda).

On doing background research for my photographs I was surprised to discover only one additional image of living Discothyrea. Considering the relative fame of the adorable little Disco ants I had anticipated more. The plate is from a 1998 study by Dejean & Dejean documenting that queens of Discothyrea oculata– one of the large African species related to D. mixta– founds colonies by moving into spider egg sacs. Here’s Dejean’s photo, apparently the first live image of this genus:

Figure 1 from Dejean & Dejean 1998.

If you know of any others, give a shout out in the comments.

Further information on Discothyrea:

source: Dejean, A, Dejean, A, 1998. How a ponerine ant acquired the most evolved mode of colony foundation. Insectes Sociaux 45: 343-346. DOI: 10.1007/s000400050093

The first live photographs of Probolomyrmex (update: no, the second live photographs)

Continuing our series of “the first photographs of X”, below are what I suspect to be the first living photographs taken of the rare subterranean ant Probolomyrmex:

Ant Course in Uganda was phenomonal. There’s nothing like having 40 keen sets of eyeballs out searching for ants in an understudied tropical forest for 10 days. Under such intense effort, all sorts of rare material turns up, including species that are almost never seen alive, much less photographed.

This particular oddity I can actually claim to have found on my own, a tiny ant less than 3 millimeters long running around under a rotting log. I brought her back to the lab to photograph so I wouldn’t lose the specimen.

That's me in the makeshift lab studio at Ant Course 2012. You can see the secret to the white backdrop. (photo by Brian Fisher)

So little is known about this ant that no one even knows what it eats. Bob Taylor (1965) kept a colony once but the ants refused everything he tried to feed them. Yet, Probolomyrmex is widespread in the tropics and occurs in the undercollected deep soil habitat, so it may be one of those animals that ends up being more common once myrmecologists figure out how to look for it.

*update (9/27): Wait! Stop the Presses! Roberto Keller points us to this photograph from Donat Agosti’s 1995 revision of the South American species:

More resources:

The first live photographs of Aenictogiton

As far as I know, I’ve just uploaded the first living photographs ever taken of the rare African ant Aenictogiton. Go see.

Aenictogiton (Kibale Forest, Uganda)

Based on genetics and morphology, this creature is probably an army ant. Someone will have to spend time finding and watching the ever-elusive workers to confirm, though.

This individual was one of the treasures collected at Ant Course/Uganda in August.

Strumigenys lujae

Strumigenys lujae (Kibale Forest, Uganda)

One perk of anting in Uganda was the lovely little Strumigenys lujae. Ants of this genus are cryptic and difficult to find in most parts of the world, yet in our corner of Africa S. lujae were in every rotting log and thick in the leaf litter.

I’ve posted a few new photos to my Strumigenys gallery.

Friday Beetle Blogging: A Buff Brentid

Now that I am back on the blog, let’s reintroduce the Friday Beetle!

Weevils are usually known for their snouts, but this muscular male brentid has foregone the typical weevil nose for a big set of chompers. Note the many mites hitchhiking on the beetle's legs. (Kibale Forest, Uganda)

Enjoying a snack break along a trail one morning in Uganda’s Kibale forest, I looked up to see a bizarre creature peering over the top of a leaf. I’d never seen anything like it. The animal was strange enough that I dropped my chocolate granola bar to take some close-in photographs. Mouthparts like a stag beetle, antennae like a weevil, and a body shaped like a tube. The ungainly animal was also covered in little mites.

Online resources for tropical beetle identification are sparse to non-existent. I am 95% confident this is a weevil in the cosmopolitan family Brentidae, however, and I suspect it *might* be Bolbocranius. If any of you recognize him, though, please drop a note in the comments.

An overhead view of the same male. More mites are visible in this aspect, too.

photo details:
Canon MP-E 65mm 1-5x macro lens on a Canon EOS 7D
ISO 400, F/13, 1/125 sec
Diffuse off-camera flash