hobo spider

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rjlittlefield
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hobo spider

Post by rjlittlefield »

Hobo spider (Tegenaria agrestis).

Top side...
Image

Bottom side...
Image

Stereo pairs of epigynum (female genitalic structure). The larger pair is designed for cross-eyed viewing, the smaller pair for parallel viewing. (Both pairs are one big image, to stay under the posting limit.)
Image

There's a story here, of course.

A couple of months ago, I posted an action picture of a small spider that might (or might not) be a hobo.

Eight weeks, three molts, and more than a few flies later, I sent an email to Rod Crawford, curator of arachnids at the University of Washington's Burke Museum.
I'm writing to you now to ask if you can help me ID a spider. A couple of photos are attached -- I don't know if they'll be adequate, but thought I'd ask now before going to the trouble to shoot better ones.

Background story is that this individual was captured live a couple of months ago by one of our summer interns at Pacific Northwest National Lab in Richland, WA.

She thought from general appearance that it might be a hobo, and asked if I could tell for sure. Well, it was only about half-grown, so I couldn't, but I did keep the beast around to see if perhaps I could get it to grow up.

Appearance when young is shown at http://www.photomacrography.net/forum/v ... php?t=3081 .

Three molts later, it now looks to me like a mature female whose epigynum structure matches the hobo in Figure 10 at http://pep.wsu.edu/pdf/PLS116_1.pdf . The coloration of mine is much less intense, but I gather that's not a strong point.

Anyway, I wonder if you can confirm, deny, or correct the ID, or let me know how much better or different pictures you would need to do that.
The reply (by permission, and in its entirety as requested) was this:
Rod Crawford wrote:Yes, I think your diagnosis is correct. It's no surprise - hobo spiders are common in every town and farming area of eastern Washington, but human bites are still rare. Females, like yours, are only minimally toxic to vertebrates - all the serious bites are from males (all dead by this time of year) and possibly juveniles.

Congratulations on hitting on the one thing to photograph that would make an ID possible. Very few people ever get past the wrong idea that coloration means something in spider ID.

---Rod Crawford, Burke Museum, Seattle, USA <tiso@u.washington.edu>

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Check out the "Spider Myths Web Site"!
http://www.washington.edu/burkemuseum/s ... index.html
and find out why everything "everybody knows" about spiders is wrong!
Many thanks to Rod for the ID and further information -- and of course I'm always eager to help dispel myths about our segmented brethren! :D

--Rik

Technical: Canon 300D. First two images using Sigma 105mm macro lens at 1:1, flash with paper towel diffuser. The subject was on its web, inside a square, clear, plastic box, photos shot through the sides of the box.

Details of the epigynum are stacked with Helicon Focus, shot with Olympus 38mm bellows macro lens set at f/5.6, 0.005" focus step. Dual fiber halogen illuminator with kleenex tissue diffuser. Live subject was confined in a "dry box" between two microscope slides, as described by this posting in the technical forum.
Last edited by rjlittlefield on Sun Nov 11, 2007 6:52 pm, edited 1 time in total.

Ken Ramos
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Post by Ken Ramos »

Beautiful photographs there Rik and the markings on the spider are really neat. I sure am glad though that the spider is not as big as it appears on the monitor though. :shock:

JoanYoung
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Post by JoanYoung »

Wonderful shots Rik. :) Thanks for all the interesting info on it.
Joan Young

rjlittlefield
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Post by rjlittlefield »

Thanks, Joan! I always learn a lot in researching these postings. Sharing is a good driver to look up even more.

Ken, I sympathize -- it does look like a bit of a monster, doesn't it? Actually it is pretty good sized for a house spider -- take a look at the tech forum posting and see how it has to tuck its legs to fit on a 1" microscope slide.

What I find most interesting about the top picture here is how it calls attention to the curved femurs of the rear legs. I never noticed that, watching the actual spider, but with the light background shining through the "bowlegs", it's hard to miss! :lol:

--Rik

JoanYoung
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Post by JoanYoung »

attention to the curved femurs of the rear legs
You are right Rik...it shows how each of us notice something different in each pic that is posted. I never noticed the bowlegs either. :)

This forum is great for learning, so I am glad Ken encouraged me to join. It is such a pity that no-one here in SA seems to be interested in putting together a "Bugguide". The only information available is scattered in little bits here and there....if one is lucky to find anything at all!!
Joan Young

rjlittlefield
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Post by rjlittlefield »

BTW, here's what the beast looks like with a familiar object for scale. 8)

--Rik

Image

JoanYoung
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Post by JoanYoung »

You won't find Ken holding it like this. :lol: :lol:
Joan Young

Danny
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Post by Danny »

Great shots there Rik. Good to see a decent environment shot and I like to last shot for scale, that always appeals.

All the best Rik, well seen and taken.

Danny.
Worry about the image that comes out of the box, rather than the box itself.

Mike B in OKlahoma
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Post by Mike B in OKlahoma »

Rik, your little girl is all grown up! Nice Senior portraits you showed us!
Mike Broderick
Oklahoma City, OK, USA

Constructive critiques of my pictures, and reposts in this forum for purposes of critique are welcome

"I must obey the inscrutable exhortations of my soul....My mandate includes weird bugs."
--Calvin

rjlittlefield
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Post by rjlittlefield »

Thanks, Mike. I'm still trying to figure out how to get that high-res stacked portrait... :-k

--Rik

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