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Photo#358594
Spider ID Request - Pisaurina dubia

Spider ID Request - Pisaurina dubia
Herring Run Watershed, Baltimore City County, Maryland, USA
November 16, 2009
Observed under a railroad tie.

Moved
Moved from Spiders.

Moved

Tibellus vs. Pisaurina
I have trouble with these. I'm actually leaning toward P. dubia on this one.

 
Good possibility
Now that I look more closely (which always helps), the posterior lateral eyes do look a little large for Tibellus, if that's what those black dots are.

 
MD
is not listed for P. dubia on the page below:
http://www.canadianarachnology.org/data/spiders/19772#image

Only MO, OK, SC, & TX are.

 
Might be P. dubia
I hadn't thought of that one! There is a record for Maryland in BugGuide:



Have you got a closeup of the eyes for your spider?

 
Unfortunately
this is all I have. The map on the Nearctic Spider site shows immatures active at the correct time of year for this. Might this be an immature P. dubia?

Also, wouldn't my finding this under a log help the determination because I've recorded finding a Pisaurina mira under a log? Compare that to the Tibellus who are associated with grass stem sitting. Notice the posture of my specimen more closely resembles the open-spread stance of a Pisaurina versus the linear-stretch position of a Tibellus.

Any thoughts/comments/feedback on this?

 
Hard to say
I think that what appear to be large posterior lateral eyes on this spider (if those black dots in the picture are those eyes) is the strongest evidence that this is Pisaurina rather than Tibellus. In Tibellus those eyes would be small.

Unfortunately, I don't know enough about the habits of Tibellus to say it would never be found under a log (possibly there to molt, for instance?) so I'll have to stick with the eyes for now.

I want to say that the median abdominal stripe now looks more like Pisaurina than Tibellus as well. In Tibellus it's suppose to extend all the way from front to back, but I'm not sure I see that so well in this spider. It looks more like it narrows about halfway back on this one.

 
Thanks
to everyone for working on this. I look forward to the seeing where it takes us -- to an impasse or a resolution.

 
pair of dots
I have also found that Tibellus usually has the paired dots towards the rear of the abdomen


and dubia has the paired dots towards the front of the abdomen

Moved
Moved from ID Request.

Running Crab Spider
Tibellus sp. (Philodromidae) There are several species and they can look very much alike. More photos and info here:

http://bugguide.net/node/view/6824

 
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