I’d like to have had this post up at 5 am sharp this morning, but that didn’t quite happen: I’ve been keeping myself quite busy over the past week with my evaniid mouthpart work. It’s been more or less a constant struggle dealing with the quirks of our imaging software, Photoshop Elements, and CombineZP to get halfway decent images, but I think, for the most part, my dry specimen images are alright. One of the discoveries I’ve made is that all of my specimens have at least some degree of a shelf to the prementum, though some are less noticeable than others as they are upturned, giving the sclerite a shape similar to an arbelos when viewed along the anteroposterior axis. I’ve come to believe that this character may be less important than I previously assumed.
I’ve moved all specimens into glycerol after a 24 hour soak in clearing solution— a mixture of lactic acid, phenol, and glacial acetic acid which, I have discovered, melts the black enamel off of insect pins— and a hour wash in distilled water. At this point I am examining the glossa, focusing particularly on the number and placement of styloconic sensilla along the apical edge of the organ.
A styloconic sensillum is different in structure from simple hair sensilla in that the body of the setae lies not directly within a membrane-bound pit in the cuticle, but within a torus shaped secondary body.
These Sensilla serve roles as both mechanoreceptors and chemoreceptors in other insect orders, but have not been as well studied in Hymenoptera.
After maxing out the hard drive on our lab computer with images of wasp mouthparts, I took a little break from dissection and dug about in the collection room while waiting for files to transfer to my external drive. I was particularly interested to see what the Frost had in terms of Strepsiptera. I went to the alcohol collection first and found a whole drawer labeled Strepsiptera.
Unfortunately, all I found in it was a bit of dust. So, my hopes unquashed, I moved on to the dry collection. I managed to find three specimens representing two taxa.
The first two were identified as Caenocholax fenyesi (Pierce) and were males collected from Archbold Biological Station in Florida by S.W. Frost himself back in 1939.
The other specimen was incorrectly labeled as Forcipomyia fuliginosa, a variety of biting midge. As this specimen was taken on Polistes, it may well be of the genus Xenos, but I have not taken the time to key it out yet.
The only suitable adjective I can come up with to describe Strepsiptera is “lovecraftian”. With their weird, raspberry like eyes, frilly antennae, membranous back wings bearing only longitudinal veins, and fore wings that are reduced to bulbous halteres they look like they belong in a work of fiction— and this is just the males! The females are typically reduced to grub-like manifestations that spend their entire adult life embedded under the abdominal sclerites of their host.
I also sifted through the Polistes in our collection and found five specimens with empty puparia embedded in them but no females or pupa.
The even stranger thing about strepsiptera is that we don’t entirely understand what they are. In the past they have been classified as a sister taxon of Diptera, Meloidae, and Ripiphoridae. Difficulty of collecting strepsipterans has limited the data set available to researchersand, and the apparent rapid evolution of the order had led to miserably jumbled phylogenetic results due to long branch attraction— a phenomenon in which unrelated clades are misinterpreted as related due to extreme convergences. Current studies suggest they are probably a sister taxon to Coleoptera, but the jury is still (and may remain) out.
Leave a Reply