Dumpster diving xanthopygine rove beetles

Let's face it, a lot of beetles are associated with ants. But few go to the extremes that rove beetles go to make themselves at home with the ants. Many rove beetles not only look like ants, they also smell like ants. If you want to see some really cool, yet ultimately bizarre beetles, I suggest you read the blog post by Joe Parker and Taro Eldredge on Pselaphinae and Aleocharinae myrmecophiles.

A few xanthopygine rove beetles are known to be associated with ants but these beetles are typically found on ant refuse piles (=dumpsters). The refuse piles are nutrient-rich, thriving micro-communities that support many types of arthropods, fungi and bacteria. Most rove beetles are there to feed on the fly larvae but we really do not know the details. Navarrete-Heredia (2001)* lists 65 genera (148 species) of rove beetles associated with leaf cutter ants, either Atta or Acromyrmex. Several xanthopygine beetles made the list, including species from the genera Glenus, Paraxenopygus, Tricholinus, Scariphaeus, Smilax and Plociopterus.

Glenus jelskii Solsky is known from refuge piles of Atta sexdens (Scheerpeltz 1936)

One striking feature of all these xanthopygines is that they are good-looking beetles. I would have expected that an insect hiding in a refuge pile would be dull-colored (why spend energy on coloration?) but most of these have shining metallic colorations with bright yellows and reds. Not sure if this is a plesiomorphic characteristic (most xanthopygines have impressive metallic coloration) or if there is an adaptive significance of the coloration.

Some xanthopygines take their Hymenoptera associations one step further: they are known from debris piles of wasps and stingless bees. One of largest (almost 3 cm) known xanthopygine rove beetle, Triacrus dilatus, is known from the debris piles of the wasp Stenopolybia Agelaia vicina (Wasmann 1902).

Triacrus dilatus Nordmann

A couple more species, Xanthopygus cyanipennis and Xenopygus analis have been recorded from the nest of Trigona clavipes (a stingless bee) (Luderwalt 1917), although both of these instances might be accidental/opportunistic. Xenopygus analis is extremely widespread (Mexico to Brazil, introduced in Hawaii) and will feed on anything. A while back I posted a video clip of X. analis eating rotting Gustavia superba fruits.

A lot of cool work remaining to be done here, both systematic and ecological, to understand these associations and map the evolution of these behaviors.


*Thanks to Adam Brunke for providing some of these references.

References

Luderwalt H (1917) Biologishes uber brasilianische Staphyliniden. Z. Wiss. Insektenbiol. 13: 44-47

Navarrete-Heredia JL (2001) Beetles associated with Atta and Acromyrmex ants (Hymenoptera: Formicidae: Attini). Transactions of the American Entomological Society 127(3): 381-429.

Scheerpeltz O (1936) Die von Prof. Dr. H. Eidmann gelegentlich seiner im Jahre 1933 nach Brasilien unternommenen Studienreise aufgesammelten Staphyliniden. I. Die in den Nestern von Atta sexdens L. aufgefundenen Staphyliniden, nebst einigen Bemerkungen uber die Gattung Scariphaeus Er. Archiv fur Naturgeschichte (N.F.), 5, 483–540.

Wasmann E (1902) Riesige Kurzflügler als Hymenopteren-Gäste. (132 Beitrag zur Kenntniss der Myrmekiphilen und Termitophilen.). Insektenborse 19: 267–268, 275–276, 282.

Beeria nematocera: The most interesting rove beetle in the world*^

A few months back I was asked to identify some Staphylinini specimens from Prince of Wales island in Alaska by Derek Sikes. If I remember correctly there were a lot of Atrecus and Quedius (pretty boring things for a neotropical rove beetle guy like me who is used to beetles like this) but one specimen made the whole sorting worthwhile:

I present to you Beeria nematocera (Casey). The species was first described by Casey who described it in Philothus from some specimens collected in the Pacific Northwest. Later Smetana (1977, paper behind paywall) transfered the species in its own genus and for a long time it was considered a "hybrid" between Philothina and Quediina. 

The species is extremely rare in collections (I will be shocked if there are more than 10 worldwide) and I know that several rove beetle systematists have sampled the type locality without being able to collect any specimens. The specimen I received was collected by Derek and students in a pitfall trap and the habitat looked like this:

Photo by D. Sikes. Original photograph here:
http://www.flickr.com/photos/alaskaent/5155883864/in/set-72157625334180410

Yeah, good luck collecting Beeria down there without a trap. 

The detailed record for the specimen can be found on the Arctos database that Derek maintains at the Museum of the North (love the name by the way), University of Alaska here and here.

A recent morphological phylogenetic analysis of Staphylinini (Brunke and Solodovnikov 2013, paper behind paywall) placed Beeria as the sister group of 'Staphylinini propria' ("Anisolinina", Staphylinina, Xanthopygina, and Philonthina). However, the particular position on the tree may be an artifact due to the lack of proper morphological characters to clearly identify the sister group of Beeria. I mean, look at the huge postcoxal process here (yellow arrow):

Now, can I have some DNA quality specimens please? 

* where 'interesting' means we have no clue where it belongs phylogenetically and I really want it for DNA work, and 'the world' really is North America here.
^ whoa, people are very geographically sensitive. I am not implying here that "the world" is North America; I was just paraphrasing the "most interesting man in the world" commercial...

The limits of morphology

I was told early on as a graduate student that an insect taxonomist should "kill first, ask questions later" during fieldwork. This was usually said in the context that you might lose a rare specimen if you spend time looking at it, rather than putting in a vial. I am here to tell you that I have deeply regretted following that advice.

Every single time I am working on a taxonomic paper I catch myself having the same wish: "I wish I had seen these specimens alive, just to get a glimpse of how they are using these structures." Morphology can tell us a lot of things but sometimes a dead insect hold its secrets very well.

Exhibit A: In a paper published in 2005, Steve Ashe and I revised the genus Philothalpus. These are striking beetles with questionable taxonomic affinities (at least according to DNA).

Philothalpus brooksi

Abdominal sternum VII

Males in this genus have a perplexing structure (indicted by a white arrow on the figure above) on the ventral side of their abdomen, specifically on the 7th abdominal sternum. Back then we called it a "porose structure". Truth is, we have no idea what it is. A hole on the body with setae around it. Only males have it. But how do they use it? I have no clue. I guess I will be inclined to accept the notion that is used in male/female interactions since it is only present in males but, boy, if only I had seen these guys alive...

The example above came to mind when I recently examined a species (in another genus) with a similar structure:

Exhibit B:

 The structure is present in the same abdominal segment (VII) but it is clearly different than the one above. Are these structures homologous?  Are they used for the same purpose? Morphology cannot answer these questions. Sure, we can do fancy evo-devo here, but that requires live specimens, identifying conserved developmental genes and so on.

What we really need is good old basic natural history observations that can solve these problems. But "kill first, ask questions later" attitudes really do not help. So, next time you are in the field, jot down some observations before you kill those insects.

A little monster from Paraguay

Long time no blog post. Well, the fall semester is here and I plan to reactivate this site. It has been pretty dormant this summer due to my travels and other joyful and not-so-joyful moments in my life over the the past few months.

I figured we will start with something impressive, the species shown below is Gastrisus nobilis (Wendeler) although the species certainly does not belong in Gastrisus. it is actually a member of a new genus (along with several other species) soon to be submitted for publication in Zootaxa. Average length of these guys is ~ 15 mm and like so many other rove beetles, really nothing is known about their biology.

Visiting the alma mater

I am going on a solo road trip next week to Lawrence, KS to work at the University of Kansas for 10 days. KU is the place where I got my Ph.D and it be will be nice to chat again with friends and colleagues. I am looking forward to the visit, although, since my family is staying back, it will probably be non-stop work for these 10 days.

When I was a graduate student, SEMC used to be in Snow Hall. Awesome building but not really built for collections. Currently, Snow Hall houses the department of Economics (how do you like the mothball smell?) and SEMC is the Public Safety Building, right next to the police department. The building is great for collections but it lacks the 19th century appeal of Snow Hall. For the first three years of my graduate career, I was in Snow Hall every single day (if I was in town). Then I met my wife.

It looks like we are going to have a mini paleontology symposium there with colleagues visiting from Spain and France. I am definitely looking forward seeing all these new fossils and perhaps I will find some time to sort out some xanthopygines.

Natural History with toddler

Lately after I pick up my daughter from daycare, we come home and we go sit on the bench in the backyard. I call this the "Banana/Natural history time" and typically involves her eating a banana, while we both unwind from our day activities. This is becoming fast my favorite time of the day. As mentioned in a famous book series "The world is quiet here" during that time.

The above-mentioned toddler during snack time

Right behind the bench, there is a little patch (maybe 1x2 square meters) of native plants. Inspired by David Haskell's book (The Forest Unseen) we have been doing daily natural history observations during the "banana time".

We have been watching ants digging new tunnels, blue-eyed grass flowering, azalea's dropping their flowers and creating pulp-like substrate and bryophytes producing their sporophytes. Now, I do realize that my 21 month daughter cannot assimilate most of that, but you got to start them early, right?

Biology related music

We all get feedback from students and frankly this two way communication is one of the best perks in the job. During the Spring semester, I was talking about conifers in my Principles of Biology II class. Specifically, I was taking about the bristlecone pines (Pinus aristata) found in the western USA and how some of those have been around for several thousand years.

One of my students later emailed me saying that my lecture reminded her of the song "Bristlecone" by the "The New Empires".  It is a lovely song and you can listen to it here.