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Unknown Spider - Antrodiaetus

Unknown Spider - Antrodiaetus
Irwin, Westmoreland County, Pennsylvania, USA
November 22, 2009
Size: Approx 3/4"
This spider was observed walking across a concrete sidewalk at mid afternoon in the sun. I am interested in knowing what kind of spider this is, if it's harmful to humans, and its beneficial values. Thanks in advance for sharing your knowledge.

Images of this individual: tag all
Unknown Spider - Antrodiaetus Unknown Spider - Antrodiaetus Unknown Spider - Antrodiaetus Unknown Spider - Antrodiaetus

Awesome find . . .
and nice images too!

Moved from Antrodiaetus unicolor.

I'm moving this post back to genus-level because there is a possibility that it could be either A. robustus or A. unicolor. Thanks to Brett and Brent for their attention on this matter!

Brett is right, this spider i
Brett is right, this spider is from an area where both species have been collected and without closer visual inspection, it is near impossible to identify these lil' buggers. Antrodiaetus unicolor is incredibly variable across its range but can be readily identified where it is sympatric with A. robustus by the type of setae on the anterior portion of the abdomen near the pedicel. I cannot tell from the photos.

I think this could possibly be Antrodiaetus robustus rather than Antrodiaetus unicolor. The location of this specimen is well within the range of A. robustus. But of course, it's difficult if not impossible to tell the difference between the two without closer examination of certain anatomical features. I've always suspected, however, that A. robustus would be stockier in overall appearance than A. unicolor, and this specimen definately looks more "robust" than the A. unicolor that I've seen in my area. But I'm just speculating here. Maybe Brent Hendrixson will chime in, he's quite the expert on this genus.

Moved from ID Request.

Nice pics!
Great images of a female foldingdoor spider, Antrodiaetus unicolor. These are "primitive" relatives of the trapdoor spiders and tarantulas. Despite their size they are not at all dangerously venomous to people or pets. Females usually stay inside their silk-lined burrows, so this is a nice find.

Foldingdoor spider, Antrodiaetus unicolor
Thank you for the identification and information on the foldingdoor spider, Antrodiaetus unicolor. With the info that you provided, I searched the foldingdoor spider in and found several similar images. Thanks again.

You're welcome
This is one of the few spider genera I know for certain. LOL! We have a similar species in Portland, Oregon where I spent my childhood....

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