Crayfishes of Georgia
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Dichotomous Key to the Crayfishes of the Ocmulgee River System

1a. Two cervical spines (Fig. 1)...........................................go to 2
1b. One or zero cervical spines............................................go to 3

 cervical spines

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

2a. Claw tubercles whitish..........................Procambarus spiculifer
2b. Claw tubercles black............................Procambarus raneyi

3a. Mesial margin of palm longer than moveable
finger..................................................................Faxonella clypeata
3b. Mesial margin of palm not longer than moveable finger......go to 4

4a. Length of mesial margin of the palm greater than width of palm (sometimes about equal on females).....................................go to 5
4b. Length of mesial margin of palm less than width of palm....go to 9

5a. Claw tubercles reddish or orangish..................................go to 6
5b. Claw tubercles not reddish or orangish............................go to 7

6a. Tip of male gonopod pointed (Fig. 2A)....Procambarus howellae
6b. Tip of male gonopod rounded (Fig. 2C).......Procambarus clarkii

howellae paeninsulanus clarkii

Figure 2. Gonopod of Form I male of A) Procambarus howellae; B) P. paeninsulanus; C) P. clarkii. Modified from Hobbs (1989).

7a. Carapace with two discrete spots on each
side..........................................................Procambarus seminolae
7b. Carapace without discrete spots (occasionally, P. enoplosternum will have spots, but there is usually dark pigment connecting them)....................................................................................go to 8

8a. Areola wide, averaging 3.6 times as long as
broad................................................Procambarus enoplosternum
8b. Areola narrow, averaging 11 times as long as broad................................................................Procambarus acutus

9a. Mesial margin of palm with jagged, irregular tubercles
(Figs. 3A, B)........................................................................go to 10
9b. Mesial margin of palm with similar sized tubercles
(Fig. 3C)..............................................................................go to 11

 caritus pyg depress webFigure 3. Claws of subgenus Hagenides [includes A) P. pygmaeus and B) P. caritus] indicating jagged tubercles along mesial margin of palm versus C) more typical margin of crayfish palm with smaller, similar sized tubercles.  Modified from Hobbs (1981).

10a. Color greenish with red highlights........Procambarus pygmaeus
10b. Color olive or purplish brown; claws may be
bluish..............................................................Procambarus caritus

11a. Mesial margin of palm with more than two rows of tubercles.............................................................................go to 12
11b. Mesial margin of palm with two rows of tubercles.........go to 13

12a. Spine extending past end of uropod
(Fig 4A.)........................................................Cambarus acanthura
12b. Spine not extending past end of uropod
(Fig. 4B)..........................................................Cambarus diogenes

tails web

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).

13a. Areola usually more than 9 times as long as broad and often obliterated (Fig. 5A); rostrum typically somewhat blunt; some populations with distinct abdominal stripes; cervical spines never present............................................................Cambarus striatus
13b. Areola usually less than 9 times as long as broad (Fig. 5B); rostrum tapering; some individuals with indistinct abdominal stripes; cervical spines sometimes present, especially in juveniles.............................................................Cambarus latimanus

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

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