Key to PA Crayfishes

Keys work by giving you two choices (thus, keys are referred to as dichotomous).  By your choice, you will be led to other couplets to make another choice until you eventually identify the crayfish.  Choose the statements that most closely describe your crayfish, even though there might be one statement that is not true and two that are.  Click the "couplet #" button at the end of the statement that is most true for your crayfish indicating what is your next step.  As you progress, use the back button in your internet browser to go back to the previous couplet numbers if you need to.  There are also buttons at the bottom to jump back to the crayfish figures or to the glossary (definitions of terms).  Use the big arrows on your web browser to get back to the step in the key.  Have fun and don't get too frustrated...some of these species are very hard to tell apart.  That's where I can help...send me an e-mail and I'll do what I can.

1a    Carapace posterior to cervical groove completely covered with raised tubercles such that the surface feels granular (fig A); male with ischial hooks on 2nd and 3rd walking legs (fig B); gonopod terminating in more than 2 elements (fig C); chelae long and slender (fig D) - Procambarus acutus acutus (Found in eastern and southeastern PA in the Delaware drainage basin.  Possibly in extreme northwestern PA. Mostly near standing water, large river banks, ditches, swamps, etc. Can burrow into mud during drier season.  Can be quite large (> 12cm).)

1b    Carapace posterior to cervical groove smooth, or possibly with a few tubercles, but not extending to dorsal surface; males with ischial hooks on 2nd walking legs only (fig A); gonopod terminating in 2 elements (figs B and C - one type or the other)--> go to couplet 2.