I finally came across an article in The Journal of Arachnology, Volume 32, Number 1, that included information and keys to the Pardosa genera and its species. It's 54 pages long and I will admit that I didn't read it all word for word...but what I did gain from some of the maps was that Iowa for sure has Pardosa moesta, P. milvina, P. tristis, and P. xerampelina. The bad news is that I don't think your spider is any of those species and I know there's WAY more Pardosa in Iowa.

...so I kept looking (I'm no quitter, lol) and came across this list of species and their relative states. Unfortunately, I don't know how dated that list is, but it helped add the following Pardosa to our Iowa list: P. distincta, P. dromaea, P.fuscula, and P. saxatilis. Of those species, I would say that P. fuscula and P. modica could be possibilities. P. distincta and P. saxatilis are too different looking to be your spider. And I am unfamiliar with what a P. dromaea even looks like, so I guess that could be something to look into, also.

A long story short:
These Pardosa are known to live in Iowa (among others that I couldn't find info on):
moesta
milvina
tristis
xerampelina
distincta
dromaea
fuscula (possibility)
modica (possibility)
saxatilis

(and there's probably more, of course)

Thanks for taking your time and effort to compile this list, Mandy. I'll look them over during the next several days.

I can do this kind of homework for the rest of my life; it never gets old. I love it! Plus, I told you I would keep looking and I like to keep my word. :)