A very Atypical spider in the family Atypidae. They are primitive and related to Tarantulas. There are two genera (Atypus and Sphodros) in the eastern US of these Purse web spiders. The Atypus is knonw only from PA. There are seven species of Sphodros. They live in burrows and weave a long tube that extends above the ground along a tree or stem or stone. One species has a horizontal tube. They grab prey through the web tube with the extra long chelicerae which you can see here. This appears to be Sphodros rufipes, the Red-legged Purseweb Spider. It appears on endangered lists but this is apparently debated. It may just be very hard to see. It has been found as far north as Missouri, Kentucky and Indiana. And now Arkansas if this is correct. I don't believe Peggy Dorris found one in her survey of the state.