Rediscovering a Darwin specimen

One of the most common questions during the last couple of weeks has been "how did you end up with a Darwin specimen?" The short answer is that I was the right person at the right time.

Here is the long answer: Insect systematists are very specialized scientists. I can identify most beetles to families. I can identify rove beetles (the family Staphylinidae) to the subfamily level and I can identify most Staphylininae (one of the subfamilies of rove beetles) to tribes and subtribes.  I can name almost all species in my taxonomic expertise (the subtribe Xanthopygina) but ask me about subfamilies of Orthoptera or Diptera and I have no clue.

Darwin's statue in BMNH

The Darwin specimen happened to belong to the subtribe Xanthopygina and I guess I was the best person in the world to tell if this was a new species and a new genus.

Back in 2008 my colleague Alexey Solodovnikov (University of Copenhagen) told me that there was a "Darwin Xanthopygine" in the Natural History Museum of London. To be honest, I think I just said "OK" and did not think much about it. Later, I even visited the BMNH and I failed to locate the specimen myself. The thing is, I was not really looking for it. My main goal during that visit was to photograph the vast type collection of Xanthopygina by Sharp. So I was really photographing types and paid little attention to unsorted materials.

Alexey later told me that he had found the Darwin specimen in a box of random unsorted Staphylinidae that included both new and historical materials. Realizing that this is a Xanthopygine, he transferred it to the unsorted materials of the genus Trigonopselaphus, as the best guess on where this specimen might belong. However, at this point neither Alexey, me or anybody at BMNH knew/realized that this specimen was considered lost according to Smith (1987)

Trigonopselaphus sp. 

Fast forward a few years and I have decided to revise the genus Trigonopselaphus (revision is in progress). Typically, one requests all described materials (types) and any unsorted/unidentified materials that belong in that genus. I requested materials from several museums, including BMNH. It was only then that I saw the Darwin specimen and quickly realized that it is a new genus and new species. But it would be another few months before I realized that the specimen was considered lost, while I compiled an inventory of all rove beetle specimens collected by Darwin.

The thing is, it takes a lot of time and preparation to be able to tell if a specimen you see is "new". If I had seen the Darwin specimen in 2004 or 2008, I would have been able to tell that is is a Xanthopygine, but I do not think I would have been able to recognize it as something new. 

Working with a Darwin specimen

Today a paper came out where I describe a new genus and species of rove beetles. The description was based on just two specimens, one from the Natural History Museum, London and one from the Museum für Naturkunde der Humboldt Universität, Berlin. We typically want to have more specimens before we describe a new species. However, I decided to go ahead with the paper for two reason (1) I have been visiting major (accessible) entomological collections for more than 12 years and I have not seen other specimens and (2) one of the specimens was collected by Darwin himself!

Below is a photograph of the holotype of the new species, Darwinilus sedarisi Chatzimanolis.

Image Copyright, The Natural History Museum, London.

The Darwin specimen was collected in 1832 and there are traces of (non water-soluble) glue on the ventral side of the specimen. You undoubtedly noticed that the specimen is "dirty".  I did not attempt to "clean" it, either physically or post processing (i.e., in Photoshop). I was both in awe and scared to death handling the specimen, so I really tried to minimize time spent handling it. To dissect the genitalia I followed the steam method described by Beulah Garner (curator of Coleoptera in the Natural History Museum, London). But I did not attempt to relax the mouthparts of move the legs, a standard practice on more recent specimens, as I did not want to press my luck.  

Here is a close up of the head, where all the dust is visible in exquisite detail:

Image Copyright, The Natural History Museum, London.

I know I could have very easily cleaned the specimen with a fine paintbrush. But in a specimen as old as this, who am I to say that the dust does not belong there, especially when it does not affect the specimen description?  In a later post I will write about how I stumble upon the specimen. 

The making of a paper: Spanish Amber edition

Recently this paper came out, describing the fauna of rove beetles in Cretaceous Spanish amber.

I thought  I would provide here some details on how I ended up collaborating with two people I did not know before.

About a year ago I got an email from David Peris, a graduate student in Spain. He had a large collection of fossil rove beetles and as part of his PhD he wanted to describe them. He had funds from Spain for a trip over the Atlantic and wanted to come here, at UTC, to work with me for a period of ~ month. It turns out that my University does not have a clue on how to host an international long term visitor  was working hard towards building in infrastructure for visiting scientists -- but nothing inexpensive was available yet. For a little while it seemed like things are not going to work out, but my good friend at the University of Kansas, Michael Engel, offered to host us both there.

David arrived in Lawrence in June and I got there a few days laters. We spent ~ 2 weeks describing and discussing beetles and I am rather proud of the end result. The bed bug bites I got at the Lawrence hotel were totally worth it (also, three new specimens of Cimex lectularius for the teaching collection). We finished all descriptions during our time in Lawrence, and then David spent a bit more time back home getting all the illustrations and photographs ready for the paper. I think we submitted the paper in September, got accepted in November and published online in January.

Also a side note about writing papers: very frequently I hear people (typically in a condescending tone) saying that taxonomists can produce papers very fast (I guess as shown above), so for example an ecologist producing 1 paper/year should not feel bad if a taxonomist produces n papers/year. Two things: (1) yes, writing a description is fast, but to get there it typically requires many years of prep work to figure out what is new and (2) productive people always produce many more papers than non-productive people, regardless of the field, simple as that.

And the most common xanthopygine rove beetles is

Xenopygus analis (Erichson). Distributed from southern Mexico all the way down to Argentina, also found in the Caribbean and introduced in Hawaii.  By far the most frequently encountered and most frequently collected Xanthopygina.

As they say, I would be a millionaire if I had a penny for each specimen I had identified in collections

around the world. With so many populations around central and south America, this is a going to be a cool phylogeography project someday. 

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.