Regressing against Ethanopium

I’m including stats in a larval description I’m working on, like, now. Give it up for Dyar’s Ratio!

I took Jim’s course on larval biology (one of the best classes I have taken, btw, and Keith still holds a grudge cause I got a better grade in the class – hey, we all miss-IDed the lymexylid larva in our collections, OK?) and learned about Dyar’s Rule/Ratio, whatever you want to call it, and Dyar’s personal weirdness (he was all about building dangerously illegal tunnels in his back yard).

Once I heard about Dyar’s Ratio, I was determined to include it in my research, and here I am, including it, but with really no utility, admittedly, but that’s OK. Just don’t tell the editors. Hey, at least the concept had never been tested in rove beetles, right?

Here’s my new fav., courtesy of Krystaal: Dengue Fever, a Cambodian Psychedelic Surf Rock influenced group. Enjoy Ethanopium a cover (also a soundtrack for Broken Flowers, FYI), but a nice segue into the band nonetheless.

Cryptic species complex in a North American Deinopsis species.

Sometimes it can be tricky deciphering the difference between intra- and inter-specific variation – differences between individuals of a given species as opposed to those that exist between representatives of different species – without consulting molecular divergence. When molecular data is lacking, taxonomists typically compare a large sampling of individuals across the available morphological variability in order to identifying species boundaries; taxonomists typically look for breaks in a seeming continuum of morphological variation.

In the case of the genus Deinopsis, there was a noticeable lack of available specimens for this sort of approach when the genus was revised in 1979. Understandable given the scarcity of Deinopsis, they seem to be a rare group.

Genitalic variation in Deinopsis harringtoni, illustrated by Klimaszewski in his revision of the genus.

Genitalic variation in Deinopsis harringtoni, illustrated by Klimaszewski’s transformative revision of the genus.

In Klimaszewski’s comprehensive revision of the genus, genitalic vatiation (a feature commonly used to distinguish species) in Deinopsis harringtoni, a rather widespread northeastern North American species, was determined to represent intra-specific variation.

Deinopsis species occur in swampy and more muddy banks of slow to stagnant bodies of water compared to Gymnusa, a related genus that I previously introduced how to collect. Incidentally, I had the opportunity to collect Deinopsis on several occasion last summer.

Exemplar Deinopsis habitat.

Exemplar Deinopsis habitat from Vermont.

Among the Deinopsis specimens I collected were two series which I had tentatively identified as D. harringtoni, but males from the two samples sported different genitalic morpho-types. Considering the possibility that this genitalic variation in fact represented species boundaries, I sequenced both D. harringtoni samples to compare their pairwise molecular divergence.

Modified by CombineZPModified by CombineZP

Low and behold, comparing partial COI sequences of the tentative D. harringtoni specimens in reference to a Palearctic species, D. erosa demonstrated over 20% sequence divergence between every pairwise comparison of the three Deinopsis specimens. The morphological differences between D. erosa and harringtoni qualitatively appear significant, suggesting that the degree of molecular divergence I found in the partical COI sequences sufficiently identifies species boundaries.

What was previously considered intra-specific variation in D. harringtoni genitalic morphology may in fact indicate boundaries between species that: geographically occupy close to overlapping ranges with little to no external morphological identifiers – Deinopsis harringtoni could be a complex of cryptic species. Pretty exciting stuff and definitely warrants more collections to be made across the country to sample more populations. This will be fun and challenging since these guys can be pretty rare.

Deinopsis spp sequences Mesquite

Masoncus drama.

Remember Masoncus?

Well, I’ve been keeping them in the lab. I’ve found that they encounter similar issues with college dorm room residents, only they don’t have door-knobs for cliche gestures.

Notice Masoncus is “invisible” to their hosts.

The lab has made its Nat Geo debut

Check out the first blog entry over at National Geographic’s Explorers Journal.

There will be field updates that will accompany the upcoming Suriname trip.

The man in the rubber suit is back.

2014, I regress to adolescent excitement. I’m sorry, it’s only the king of all beasts.

Image

Parts of the gland are sclerotized

Preparing glands for SEM imaging – making pelts of glands. Potassium hydroxide digestion leaves behind the sclerotized gland reservoir and ducts, while removing unwanted soft tissue.

dissecting_glands

An image showing a concentration of D1 gland cell ducts.

Myrmedonota nr. defensive glands

Glands

Developing abdominal defensive gland in a 48 hour old Atheta coriaria pupa. Already a dense outline of type 1, D2 epidermal secretory cells are visible outlining the glandular reservoir, which itself is derived from the intersegmental membrane between tergites VI and VII. Pupal duration is approximately 96 hours long in this species.

The arrow indicates the cell-dense intersegmental invagination which is the defensive gland reservoir.

The arrow indicates the cell-dense intersegmental invagination which is the defensive gland reservoir.

And another view.

And another view.

These images were taken with the help of entomology Steve. Thin sections were taken in epoxy embedded samples, then colored in a general stain – hence the blue. Thanks Steve!

Big fan of strong, attitude-pumped female vocal-centric groups, not to mentioned, I’m kinda into electro-pop right now. As I have, please totally rock out as you carefully contemplate the gland images as a representation of a key innovation – a key innovation that compartmentalized bodily glandular tissue into a collective organ, helps natural selection do it’s thing this way, at least that’s my working hypothesis. I said it first, just saying.