Monday, June 20, 2016

Plociopterus ain't no myrmecophile!

In a paper just published in Coleopterists Bulletin (pdf here), Mariana Chani-Posse and I moved two myrmecophilous species of “Xanthopygina” in Philonthina. Both species had been described by Wasmann 1925 in the genus Plociopterus. And so for the last 90 or so years, Plociopterus was known to have two myrmecophilous species. Unfortunately, several authors discussing the origin of myrmecophily in Staphylinidae (or at least specifically for Staphylinini) was using this as an example of independent evolution of myrmecophilous life style. The problem was that nobody had checked the specimens since the original description, because none of those species belonged in Plociopterus. They are Belonuchus (at least until the genus is revised) and for those keeping score at home, this is also the wrong subtribe…

The moral of the story is this: people make mistakes and generic concepts change over time, as well as our understanding or higher level relationships. As I have mentioned earlier, If somebody described a taxon 100 years ago, chances are that this taxon now belongs in a different genus or is a synonym of something else. Using raw data in biodiversity studies without going through the lens of a revision is almost guaranteed to lead to erroneous results.

As a side note, Plociopterus is in terrible need of a revision. There are multiple new species awaiting description and many taxa that have to be placed in synonymy. But the genus has an infamous history among Xanthopygina workers: at least twice people have started its revision (both in the lab of my late PhD advisor, Steve Ashe) and both times people abandoned the effort. Perhaps third time’s the charm?

Wednesday, June 8, 2016

Thoughts on studies using taxonomic data

tl;dr version: Your results are mostly wrong. Unless someone has revised (in a taxonomic sense) the species you are using in your study.

Longer version: People make mistakes. When we describe a new species, or a group of new species, we sometimes place them in a taxonomic rank (let’s say genus for argument’s sake) we think is correct but we cannot be absolutely sure, unless we have a very thorough phylogenetic analysis. Phylogenetic analyses are awesome, but in the age of genomics they cost a lot of money. And in many cases (incorrectly in my view), building that phylogeny is beyond the interest of the person describing these taxa.

Now consider that the majority of species were described a long time ago, long before people were thinking about phylogenetic relationships. Also, some of the early (we are talking 19-early 20th century here) taxonomists were not specialist per se, and would describe species among many different families of insects, thus not really knowing where those species belong. So, in many cases, if during the last 40 years nobody has taxonomically checked (=revise) the species you are are using, chances are that these species are: (a) synonyms of another species; (b) placed in the wrong genus or (c) placed in the wrong higher rank.

Example: in 2004 I published with several colleagues a study on when (day or night) rove beetles were active on Barro Colorado Island, Panama. If you want to read the details, the paper is here, but to save you from a lot of trouble, I just set up a flight intercept trap and for a period of 12 days I was sampling at dawn and dusk. Here is part of table 1:

My 2004 self made two three mistakes there. What we thought was Dysanellus ended up being a new genus of rove beetles described as Zackfalinus and Dysanellus is restricted to the southern part of South America. Likewise, what we thought was Philothalpus ended up being Oligotergus, because nobody had looked up before how messed up the generic limits were in Philothalpus. UPDATE: Adam Brunke correctly reminded me that all specimens identified as Quedius were indeed Cyrtoquedius based on this paper.

What I am saying is this: if you are pulling data out of a digitized collection of GBIF, good luck. I hope a taxonomist was interested in the taxa you want to use.

Of course, this idea is not new. Meier and Dikow (2004) have said this much more eloquently. 

Monday, June 6, 2016

Hiding place

Every time I need to finish a manuscript I have to find a hiding place: a place where I am going to take my laptop and a bunch of papers and write. Although I can write in my office or at home, when I need to really focus to finish that paragraph in either a paper or a proposal, I have to get away. No matter how much I clean my office from distractions, there is always something: a specimen, a knock on the door, a stupid post-it note on my computer screen. Today my hiding spot is in unused biology lab. The gentle him of the refrigerator and the mowers outside provide enough white noise to write and even take breaks from writing to write this little note.