Around 15 to 18mm we think.

Does your measurement include the legs? I suspect that your spider is a Philodromus like you thought, but their body size (from fangs to tip of abdomen) only ranges from about 3-7mm. Your spider's 2nd leg is longer than it's first which is usually a good sign its in the Philodromidae family, although that alone doesn't identify it. If your spider's body length is upwards of 15mm as you said, then I'm not sure which direction to go except into the 'Flatties' (Selenopids)...which I am pretty positive its not. I will try to see what info I can dig up about a Philodromid with extremely hairy legs. I guess I've accomplished nothing with this reply, but I'll post it anyways. lol

No we were guesstimating the length of the body (carapace and abdomen) only. It was definitely bigger than 8mm. I should have put something near it for a comparison but didn't dare as it was very "nervous" and as I said, very fast.

And it probably ran side-ways like a crab? I really wish I could get this ID'd to a species for you. I would really like to know what it is myself. My researching failed to dig up anything useful. I'm pretty certain it has to be Philodromus, although Thanatus can sometimes look similar. Philodromus' are notoriously hairy but I have never seen one like this (extremely long only on dorsal aspects). The carapace and even most of the abdomen is seemingly patternless/colorless. Most of the species that I know of have a wide stripe down their carapce. Dorsal patterns are not always the same though, even between the same species. The size of yours is leaving me a little puzzled, but I'm sure it's quite possibly just a larger adult female Philodromus. I guess I'm just 'jabbering' too much now. I hope that some other people will chime in and help us out here. If not, I guess I can take it to Rod Crawford, although I'm sure he'd prefer an epigyne photo. It would be worth a try though.

You got it, Mandy. This is a dead ringer for Philodromus vulgaris, and a female (hairy legs and all, LOL!).

Thank you, Eric! I have never seen a vulgaris before, nor do I know anything about it. Do you know if they are notoriously extra hairy like this? Or is this one sort of an exception?

Oh, and for the Lavers...if you are interested at all, there is this checklist by Peggy Dorris, Ph.D. that lists the species of Arkansas. Unfortunately, that's the only thing it does really...there are no photos or tips on identifying. But nonetheless, there's a link to it just in case it might tickle your fancy.

Mandy and Eric for the i.d. We are aware of the Dorris list, it is linked on Herschel's site...but no help with the i.d. Our old Kaston How to know the Spiders got us as far as Philodromus but he doesn't show vulgaris. From now on we travel with a small ruler to get a better idea of size!