What do Tatuidris armadillo ants eat?

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Check this out:

It’s the first video of live Tatuidris, among the rarest and least understood of all ants. Until recently, no one had even seen one alive. The video is from a new paper in Insect Science, where a team of Belgian myrmecologists report their observations on a recent collection of live specimens. Here’s the abstract:

Ants of the genus Tatuidris Brown and Kempf (Formicidae: Agroecomyrmecinae) generally occur at low abundances in forests of Central and South America. Their morphological peculiarities, such as mandibular brushes, are presumably linked with specialized predatory habits. Our aims were to (1) assess the Tatuidris abundance in an evergreen premontane forest of Ecuador; (2) detail morphological characteristics and feeding behavior of Tatuidris; and (3) define the position of Tatuidris in the food web. A total of 465 litter samples were collected. For the first time, liveTatuidris individuals were observed. Various potential food sources were offered to them. A nitrogen stable isotope ratio analysis (15N/14N) was conducted on Tatuidris tatusia, other ants, and common organisms from the leaf-litter mesofauna. We found a relatively high abundance of T. tatusia in the site. Live individuals did not feed on any of the food sources offered, as usually observed with diet specialist ants. The isotope analysis revealed that T. tatusia is one of the top predators of the leaf-litter food web.

So Tatuidris is a top micro-predator. But of what?


sources:  Jacquemin J, Delsinne T, Maraun M, Leponce M. 2014. Trophic ecology of the armadillo ant, Tatuidris tatusia, assessed by stable isotopes and behavioral observations. Journal of Insect Science 14(108). Available online: http://www.insectscience.org/14.108.

Greibenow, Z. 2014. Glimpsing Armadillo Ants. Gentle Centipede blog: http://gentlecentipede.blogspot.com/2014/05/glimpsing-armadillo-ants.html

Soil-Nesting Ants Don’t Always Nest Directly In Soil

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Most ants live underground, but that doesn’t mean they spend much time in direct contact with the soil. Some nests are worth a detailed look, as not all tunnels through the dirt are as simple as they may first appear:

Polyrhachis (Campomyrma) sp.

This Australian Polyrhachis (Campomyrma) has lined its galleries with a fine wood pulp. I took this photograph last month in southern Australia. In the field, I was far too focused on the ants and their larvae to notice the carton substrate. At least, not right away. But once aware of it, I saw that every nest I uncovered had the pulp wallpaper.

This unusual use of organic matter likely provides the benefit of being better insulated and less prone to flooding or drying out than bare soil. The structure may also be a type of carton, meaning it also holds a connective fungus, but I was unable to find any published literature confirming it. In any case, ant nests themselves can be just as surprising as their hosts.


additional reading: Robson, S. K., & Kohout, R. J. (2007).  A review of the nesting habits and socioecology of the ant genus Polyrhachis Fr. SmithAsian Myrmecology1, 81-99.

Sunday Night Movie: Look Deep Into My Eyes

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This hypnotic clip, taken by JerseyBug, is a glimpse into one of the most fascinating set of eyes among all animals, those of jumping spiders:

The spider’s anterior median eyes (the big ones) focus sharply and can even detect depth, but their abilities are limited by an extremely narrow field of vision. Spiders counteract the narrowness by moving some of the internal elements, allowing the animal to scan more broadly. Thus, the odd color changes in this jumper’s eyes are essentially the spider having a look about.

The Yellow Crazy Ant, Anoplolepis gracilipes

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Anoplolepis gracilipes

A yellow crazy ant, Anoplolepis gracilipes, from an infestation in Cairns, Australia.

I’ve been increasingly self-conscious about not having photographed the yellow crazy ant, Anoplolepis gracilipes. This species is one of the world’s most damaging invasive insects, wiping out entire faunas as it spreads like a formic acid carpet across the south pacific. The famous Christmas Island crabs, for example, are in danger of extinction from the ant menace. For a professional ant photographer to be without photos of this little terror is to be a bookstore without Harry Potter, or a coffee shop without scones.

Thanks to ant researcher Lori Lach, though, I was able to remedy this oversight. Lori took me to one of the infested sites near Cairns earlier this month. It was like a horror movie:

Lori Lach in an invaded riparian forest, with media commentary.

Well, not *exactly* like a horror movie. But still. I had never seen anything like it.

A trail of yellow crazy ants covers a tree trunk.

The ants are big. Most invasive ant species have large colonies of rather small ants, but Anoplolepis has large colonies of large ants. Viscerally, that makes a difference. Especially since they are also fast. Much more of the ground and foliage seems to be moving. Even for an ant guy, the effect is unnerving.

Anoplolepis gracilipes

A worker collects honeydew from a sugarcane whitefly.

Anoplolepis gracilipes

Grass aphids were another source of honeydew.

I was told not to be impressed, though, because that particular site had been treated recently and the infestation was “light”. It didn’t look light to me. I saw hardly any other ants and very few insects apart from the honeydew-producing bugs the ants were guarding. A heavy infestation must be… crazy.

Anoplolepis gracilipes

Anyway. Check out the new photographs:

Yellow Crazy Ant Photos

And, if you’d like a yellow crazy ant explainer Minute Earth has a short video.

A Myrmicine Phylogeny Shakes Things Up

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Monomorium kiliani

Monomorium kiliani, an Australian myrmicine. The narrow, two-segmented waist is characteristic of this subfamily.

We’re only halfway through the year, but already 2014 will be remembered as pivotal for studies of ant evolution and classification. Following right on the heels of Schmidt & Shattuck’s massive ponerine revision comes an important new study from the Ant Tree of Life group. Ward, Brady, Fisher, and Schultz (2014) have reconstructed the first thorough genus-level phylogeny of the great ant subfamily Myrmicinae.

How important is this study?

Roughly half of all ants are myrmicines, both in abundance and in species diversity. Their numbers include fire ants, harvester ants, leafcutter ants, big-headed ants, acrobat ants, and so on, to the tune of some 6,000+ species.

So… Boom! Suddenly, we’ve been given a detailed picture of the evolution of half the ants. This is big. It is so big I cannot cover the paper in detail. Instead, I’ll just give a few preliminary thoughts, as follows:

1. This is a well executed study, as we’ve come to expect from the Ant Tree of Life team, applying a thorough analysis to over 250 carefully selected taxa and 11 genes. It’s also a shining example of an older generation of genetic techniques, alas, and while I am confident the stronger results will mostly endure, be aware that an incoming next-gen tide of full genomes, and the 6,000 yet-unsampled myrmicine species, may yet overturn some of the findings.

2. The deep history of Myrmicinae, starting 100 million or so years ago, mostly occurred on those continents that drifted to become the Americas. Echos of these earliest divisions are heard in six clear, genetically distinct groups that Ward et al have formally set the up as a new system of tribes, replacing an earlier, messier scheme. The six groups are listed here in their order of divergence: Myrmicini (MyrmicaManica), Pogonomyrmecini (Hylomyrma & Pogonomyrmex), Stenammini (AphaenogasterMessorStenamma, and relatives), and three sprawling groups with thousands of species: Solenopsidini, Attini, and Crematogastrini. 

mtree1

The myrmicine big picture. (Sharpie on office paper, 2014, limited edition print available, unless I recycle it).

3. The news is not all good. The clarity deep in Ward et al‘s tree fades for slightly younger events. Early relationships within some of the the six tribes are discouragingly ambiguous. This study has resolved some problems, myrmicine taxonomists face a difficult road ahead. Many of the world’s greatest genera do not form natural groups and will have to be redone. These include Aphaenogaster, Pheidole, Tetramorium, and especially Monomorium, which splatters almost comically across the Solenopsidines.

What, really, is Monomorium? Modified from Figure 1 of Ward et al (2014).

Distressingly, fuzzy resolution in a data set with this many markers and taxa means achieving proper resolution, if at all, will likely be expensive. Myrmicines may have speciated so explosively that we may never be able to reconstruct what happened with confidence.

4. The authors correct a few of the more obvious instances of paraphyly. Notably, the New World “Messor“, being unrelated to their old world doppelgangers, were moved to a revived Veromessor, and several social parasites like Protomognathus and Anergates have been sunk into the host genera from whence they evolved: Temnothorax and Tetramorium, respectively. There are other changes, too; they are listed in the abstract

Most of the identified problems- such as what to do with Monomorium and Aphaenogaster- were left for targeted future research.

5. Remember the dispute over Pyramica vs. Strumigenys? The argument was fundamentally over how ant mandibles evolve. Apparently, high energy trap-jaws arise easier than anyone imagined. According to Ward  et al, not only is the assemblage of trap-jaw ants formerly included in dacetini a polyphyletic splatter, even within the genus Strumigenys the trap jaw has arisen at least twice.

ward1

A phylogram of Strumigenys, modified from Figure 1 in Ward et al 2014, showing strong support for the parallel evolution of trap-jaws in the genus.

6. The rare and bizarre African myrmicine genus Ankylomyrma is not a myrmicine at all! Rather, Ward et al‘s results unambiguously tie it to the equally bizarre Tatuidris of the Neotropics, sitting on a distant branch of the ant tree. Peas in a poneromorph pod…

Ultimately, Ward et al have crafted a sobering view of how little we still know about ant evolution, and how much remains to be done.

fulva10j

Aphaenogaster fulva, photographed in Illinois.


source: Ward PS, Brady SG, Fisher BL, Schultz TR (2014) The evolution of myrmicine ants: phylogeny and biogeography of a hyperdiverse ant clade (Hymenoptera: Formicidae). Systematic Entomology, online early. DOI: 10.1111/syen.12090

disclosure: I received my Ph.D. from Phil Ward’s lab where much of this study was completed, and I contributed a few of the samples, but I was long gone by the time the study was initiated and have had no other involvement with the research.

A Texan Future For Myrmecos

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texana20ut

Atta texana - photographed at Brackenridge Field Laboratory at the University of Texas in Austin.

 

Big news!

On January 1st I will be starting as Curator of Entomology at the University of Texas in Austin.* I can’t even begin to convey how excited I am about this unexpected progression of my career. I will be managing a working research collection of over 1 million invertebrates, teaching entomology, and returning in full to ant evolution research. Mrs. Myrmecos (who has concurrently landed a postdoctoral spot in Nancy Moran’s microbiome evolution lab) and I are looking forward to this move for hundreds- perhaps even thousands!- of reasons. Among them: the caliber of our colleagues at UT, the fantastic research environment, the vibrant Austin culture, our many friends in town, a rich subtropical insect fauna. Plus, there are nests of Atta texana leafcutter ants right outside my new office. I mean, really. It’s like the search committee planted them there on purpose.

I mentioned this move was unexpected, and it really was. I began the year with no intention of anything other than moving forward with the insect photography business. My toes had been out the academic job pool since I went indie in 2011, and I’ve been happy running my own show. But a recent visit to the Austin revealed that the particulars of this curator position could be an unusually close fit for both me and for the University of Texas. So, I jumped. We’ll be pulling up our prairie stakes and moving in late fall.

See you in Texas!
 


*Since nearly everyone who heard the news asked about it, the photo business will continue as a sideline, as it was for many years before I went full-time. The insect photography galleries will remain in place, accumulating new content as time allows. I will no longer have time for private lessons and commissions, alas. The BugShot series of workshops is awesome, of course, and will live on.