Trapdoor Spider

Subject: Tarantula maybe
Location: San Antonio, TX
September 19, 2014 6:16 am
Can you help me identify this spider I found floating in my pool. When I got it out I was surprised it was alive. It is about 2 inches long and the body is 1/2 inch wide. I did not see it spread out its legs. Is it dangerous?
Signature: Lisa

Trapdoor Spider
Trapdoor Spider

Dear Lisa,
This is a Trapdoor Spider, and though it is theoretically not a Tarantula, it is classified with the Tarantulas in the infraorder Mygalomorphae, and according to BugGuide, the Mygalomorphs are:  “Easily distinguished from araneomorphs by two pairs of booklungs; fangs and chelicerae are parallel to the body axis.”
  BugGuide also notes:  “This is a more primitive group of spiders which includes the infamous tarantulas, primarily represented by members of Family Theraphosidae. Other familiar members include the trapdoor spiders and purseweb spiders.

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