Tuesday, May 17, 2011

Type specimens: Will the real slim [insert species name here] please stand up?

I've spent the past month or so re-curating our type collection of fishes and I just finished! This was great fun given the importance of type specimens in biology. A type specimen is the "name bearer" for a given species. That is, when a biologist discovers and describes a new species, he or she designates a single specimen to be the official representative of that species. As alluded to in the title of this post, I always think about the Eminem song The Real Slim Shady when I think about type specimens: if anyone ever wanted the "real" entity for any species to figuratively stand up, a biologist would go fetch you the type specimen. We designate type specimens this way so that if future researchers, for example, find an individual or a population that is similar to a known species but they suspect might be a new species, there is no question about which specimen of the known species they should compare it to. Type specimens are always the reference point when making any species updates and revisions.

Species updates and revisions actually happen more often than one might think! Systematic biologists (those who study life's diversity) are constantly acquiring new data that can lead them to discover that one species is really multiple species (this is called splitting), or to discover that groups that were thought to be different species are really only one (this is called synonymization, or lumping). Then of course there are always the discoveries of entirely new forms previously unknown to us humans, which are perhaps the most exciting type of update...

The changing nature of species boundaries (like that of scientific knowledge in general!) actually made cataloging and labeling our type collection an interesting job. Some species designations have stood the test of time. For example, we have the type specimen for the vermiculate electric ray, Narcine vermiculatus. It was originally described as Narcine vermiculatus in 1928 by Charles Breder, and today the species represented by this type specimen is still known as Narcine vermiculatus. Here's our type specimen:


On the other hand, some species names have not stood the test of time. For example, we have the type specimens for a dragonfish that was described as Flagellostomias tyrannus by Albert Parr in 1927. Here is one of them:


This species was synonymized with (shown to be the same species as) Flagellostomias boureei, in 1964 however, so any specimens that were once considered Flagellostomias tyrannus are now considered to be Flagellostomias boureei.

Our usual practice for labeling specimens in the collection is to label specimens with their current valid name. But these type specimens are well, special. No matter how the species is reclassified, the type specimen for a particular name will always be the type specimen tied to that name. And with new data, a  species name that has become invalid could be come valid again. So it's essential to preserve the linkage between the type specimen and its original name.

So here's the label template we made to solve this little dilemma -- that is, whether to label our types with the current name, or the original name. We labeled them with the original name in bold, and the current name designated underneath:


This works especially well because we keep our type specimens in their own section of the collection, not interspersed with the rest of the specimens.

It turns out that here at Peabody Vertebrate Zoology we have one of the largest ichthyological type collections in the United States and Canada (Poss & Collette 1995). Pretty cool, huh? For the next few posts I'll be featuring some of my favorites.


References:

Poss, S.G. and B.B. Collette. Second Survey of Fish Collections in the United States and Canada. Copeia 1995: 48-70.

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