From someone in South Alabama let me throw in my two-cents worth about
Lampsilis straminea straminea and Lampsilis straminea claibornensis:
Lampsilis straminea straminea is indeed limited to streams above the fall line
in Alabama and small streams at that.  Lampsilis straminea claibornensis is
found above and below the fall line and ranges from Louisiana to Florida.  Its
type locality is indeed Claiborne, Alabama.   Many workers in the region treat
the two as separate species.  I know the 1988 AFS list reports them as
subspecies.  I haven't seen the new AFS list so I am not aware of its current
"official" status.  I join with those in the region who treats them as
separate species.  I have collected both and have seen hundreds of specimens.
Until proven wrong by genetic evalutation, this is my stance.
 
Doug Shelton
Alabama Malacological Research Center
2370-G Hillcrest Road #236
Mobile, AL 36695