Key to the Crayfishes of the Tennessee River System

1a. Claws long and slender; mesial margin of the palm nearly
twice as long as width of palm (Fig. 1A)......Procambarus lophotus
1b. Claws appear more robust; length of mesial margin of the palm
equal to or less than width of palm (Figs. 1A, B)...................go to 2

Figure 1. Representative claw shapes of A) Cambarus sp. B) Orconectes sp. and C) Procambarus lophotus. Modified from Hobbs (1981).

2a. Outside edge of claw black; black spot on palm near junction of
moveable finger....................................................................go to 3
2b. Outside edge of claw not black; no black spot on palm near
junction of moveable finger...................................................go to 4

Figure 2. Dorsal view of crayfish claws indicating A) gaping and B) non-gaping condition.  Modified from Hobbs (1981).

3a. Claws gaping when fingers are closed (Fig. 2A)...Orconectes forceps
3b. Claws not gaping when fingers closed (Fig. 2B)...Orconectes erichsonianus

4a. Claws gaping when fingers are closed (Fig. 2A)................go to 5
4b. Claws not gaping when fingers are closed (Fig. 2B)..........go to 6

5a. Brown saddle pattern on carapace and wide dark stripe down center of abdomen..........................................Cambarus girardianus
5b.  No obvious pattern..................................Cambarus longirostris

Figure 3. Position of spine on mesial ramus of uropod.  A) Spine extending past edge of uropod; B) spine not extending past edge of uropod.  Modified from Hobbs (1981).

6a.  Spine extending beyond edge of uropod (Fig. 3A)......Cambarus acanthura
6b.  Spine not extending beyond edge of uropod (Fig. 3B)......go to 7

Figure 4. Dorsal view of crayfish claws indicating A) single row of tubercles along mesial margin of palm and B) more than one row of tubercles along mesial margin of palm.  Modified from Hobbs (1981).

7a. Single row of tubercles along the mesial margin of the palm
(Fig. 4A)..........................................................................go to 8
7b. Two or more rows of tubercles along the mesial margin of
the palm (Fig. 4B).............................................................go to 9

8a. Suborbital angle obtuse; some pattern on abdomen (only known from Murphy Hollow Creek, Dade County)............Cambarus distans
8b. Suborbital angle acute; no pattern on body...Cambarus parvoculus

9a. Abdomen with bold striped pattern; stripes do not continue
onto carapace................................................Cambarus extraneus
9b. Abdomen only occasionally striped;  if abdominal stripe present, light center stripe continues onto carapace.......Cambarus striatus

Figure 5. Dorsal view of A) Cambarus bartonii cavatus and B) Cambarus unestami indicating eye size and rostrum shape. From Hobbs (1989).

10a. Eyes small; rostrum squarish and parallel-sided
(Fig. 5A)...................................................Cambarus bartonii cavatus
10b. Eyes large; rostrum tapering (Fig. 5B)........Cambarus unestami