Dichotomous Key to the Crayfishes of the Coosa/Oostanaula River Systems

1a. Two cervical spines (Fig. 1A)...................Procambarus spiculifer
1b. One or zero cervical spines (Fig. 1B)..................................go to 2

Figure 1. Lateral view of crayfish indicating number and position of cervical spines. Modified from Hobbs (1981).

2a. Claws long and slender, mesial margin of palm nearly as long as moveable finger (Fig. 2C)...........................Procambarus lophotus
2b. Claws robust, mesial margin of palm only about half as long as moveable finger (Figs. 2A, B)...............................................go to 3

Figure 2. Representative claw shapes of A) Cambarus sp.;
B) Orconectes sp.; and C) Procambarus lophotus.

3a. Claws gaping when fingers closed (Fig. 3A), no rostral marginal spines or tubercles..........................................Cambarus manningi
3b. Claws not gaping when fingers closed (Fig. 3B); (claw of large Cambarus coosae may be gaping somewhat but will have marginal spines or tubercles)..............................................................go to 4

Figure 3. Dorsal view of crayfish claws indicating A) gaping and B) non-gaping condition.  Modified from Hobbs (1981).

4a. Lateral edge of claw black, fingers of claw with black preapical band....................................................................................go to 5
4b. No black pigment present on claws.................................go to 6

5a. Rear margin of abdominal segments red......Orconectes spinosus
5b. Rear margin of abdominal segments brownish (only two
records of the species from the Coosa/Oostanaula systems)..................................................Orconectes erichsonianus

6a. Spine extending past edge of uropod
(Fig 4A).........................................................Cambarus acanthura
6b. Spine not extending past edge of uropod (Fig. 3B).............go to 7

Figure 4. 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).

7a. Well developed cervical (sharp) spine that is reddish or orangish
in color; rostral margins and claw tubercles reddish or orangish..............................................................Cambarus coosae
7b. Cervical spine usually reduced to rounded tubercle; if sharp,
never red in color.................................................................go to 8

8a. Areola usually more than 9 times as long as broad; rostrum
typically somewhat blunt; some populations with distinct abdominal stripes; cervical spines never present..................Cambarus striatus

8b. Areola usually less than 9 times as long as broad; rostrum
tapering; some individuals with indistinct abdominal stripes;
cervical spines sometimes present, especially in
juveniles........................................................Cambarus latimanus

Figure 5. Dorsal view of A) Cambarus striatus showing typically narrower areola than areola of B) C. latimanus.  Modified from Hobbs (1981).