At the Commission's urging, there are two research projects up for funding by the Wild Resource Conservation Fund this year that will begin to address the lack of information regarding these important crustaceans. One will attempt to develop a photographic key to the Pennsylvania species for use by persons such as yourself. The other project would involve researchers in a coordinated effort to determine the statewide distribution of crayfishes in Pennsylvania and compare that to the early 1900's data. Whether these projects are funded depends on the amount of money that is available from the Fund this year. Across North America most researchers are beginning to realize that aquatic invertebrates are the most endangered of all species due to alterations of the aquatic environment.
Freshwater mussels are highest on the list of concern but crayfishes are running a close second.
We expect to see increased interest, studies and new information about these species becoming available in the next few years. A university library is your best bet.