Wednesday, February 22, 2012

Collecting with Mr. Williamson

I am currently working up the text for Tachopteryx thoreyi in Michigan for the Michigan Odonata Atlas. We don't have many MI records, mostly because there are only three counties (Berrien, Cass, & St. Joseph)where they are known, as MI is at the northern limit of the range in the Midwest. Second reason is that they inhabit wooded hillsides with perennial seeps -- which are not too common here.

The Gray Petaltail is a member of what is considered an archaic family of dragonflies, the Petaluridae. One thing that makes them different from other Odonata is that the larvae are semi-terrestrial and breathe air, venturing around at night to capture terrestrial prey. Sid Dunkle probably wrote as good a paper as can be done on the species in 1981, as he monitored a population in northern Florida, reared specimens, and watched marked individuals through their flight period (Dunkle, S. W. 1981. The ecology and behavior of Tachopteryx thoreyi (Hagen) (Anisoptera: Petaluridae). Odonatologica 10:189-199.). As interesting and useful as that paper is, I looked up an earlier paper by E.B. Williamson in Entomological News from 1901. I then wondered if we had the specimens that he observed in SW Pennsylvania in the UMMZ collection -- and we did. The oldest specimen was collected in 1899. Okay, that's only 113 years ago.

What really caught my eye though, was the specimen from Indiana that was the first state record, collected by C.C. Deam (who was a good friend of EBW's and is famous as a botanist in Indiana). Although the paper triangle is mottled and browned, the specimen is still in great condition.

Since we have Williamson's collection, we have a good number of T. thoreyi from Indiana, Pennsylvania, Missouri, and elsewhere (but only one for Michigan, collected by T.H. Hubbell in 1918). Farther on in the drawer, were later specimens collected in Indiana by Williamson. What makes them so interesting is that each specimen is accompanied with a small entry like that in a field notebook, but written on the paper triangle in pencil or fountain pen. Here is one example:

The text reads: "Tachopteryx thoreyi ♀
Mud Creek in Peabody Woods,Cass Co., Ind.
6/23/1929
La C., Eli C., & EBW
“Only one seen – flew in and alighted 5 feet high in large tree near creek in pasture. At pool at base of tree took Ischnura posita, Chromagrion conditum and Amphiagrion saucium.(over) Taken at 4 pm, day partly cloudy, rather warm, and windy. Hunted about but could find no others."

The other paper triangles have even more information regarding prey taken by the adults, and other tidbits of behavior. These are invaluable not just for their status as vouchers, but the additional information is something that made me feel as though I was on that trip with E.B. Williamson, watching for petaltails in the wet Indiana woods. This also points out why properly maintaining collections is so very important. There may be additional information associated with a specimen -- whether it's in a field notebook, computer file, or written on an envelope. These examples of fieldwork by an astute and tireless Odonatologist are paying dividends nearly a century after they were collected. This is why we maintain collections in perpetuity -- we are stewards of the flora and fauna that people like Williamson worked so hard to acquire. Their value is inestimable, but certainly tangible to someone looking to find what was at that spot in Indiana. I used Acme Mapper to search for the Cass Co. site, and it took me to a place that is a possible match. I wonder if Gray Petaltails still fly there?

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