Crayfishes of Georgia
Crayfishes of Georgia Overview List of Georgia Species Species Lists by Drainage Crayfish Identification Keys by Drainage Ecology and Life History Links and Other Useful Information Glossary
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Dichotomous Key to the Crayfishes of the Ogeechee River System

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

cervical spines

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

2a. Mesial margin of palm longer than moveable
finger..............................................................Faxonella clypeata
2b. Mesial margin of palm shorter than moveable finger........go to 3

3a. Claws with red or orange tubercles....Procambarus troglodytes
3b. Claws without red or orange tubercles............................go to 4

4a. Length of areola averages 10 times or more longer than areola width..................................................................................go to 5
Note: Although P. acutus usually keys here, it will sometimes have a slightly wider areola.
4b. Length of areola averages less than 10 times as long as areola width....................................................................................go to 9

5a. Greatest width of palm less than length of mesial margin of
palm..............................................................Procambarus acutus
5b. Greatest width of palm greater than length of mesial margin of palm.....................................................................................go to 6

advena pyg depress web

Figure 2. A) Claw of A) Procambarus pygmaeus and
B) P. advena 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).

6a. Mesial margin of palm with jagged, irregular tubercles
(Figs. 2A, B).........................................…………………go to 7
6b. Mesial margin of palm with similar sized tubercles
(Fig. 2C)..........................................................Cambarus reflexus

7a. Color greenish with red highlights.......Procambarus pygmaeus
7b. Color brownish with pink or bluish hues.........................go to 8

 advena truculentus web

Figure 3. Left gonopods of A) Form II Procambarus advena;
B) Form I P. advena; C) Form II P. truculentus; D) Form I P. truculentus. Modified from Hobbs (1981).

8a. Male gonopod hatchet shaped (Figs. 3C, D); rostrum broad, spatulate................................................Procambarus truculentus
8b. Male gonopod not hatchet shaped (Figs. 3A, B);
rostrum narrower, pointed...............................Procambarus advena

9a. Dorsal portion of rostrum with dense
setae.........................................................Procambarus pubescens
9b. Dorsal portion of rostrum with at most scattered
setae...................................................................................go to 10

10a. Upper sides of carapace with either large spots or
stripes.................................................................................go to 11
10b. Upper sides of carapace without large spots or
stripes.................................................................................go to 15

11a.  Areola usually greater than 6 times as long as wide...................................................................Procambarus lunzi
11b. Areola usually less than 6 times as long as wide............go to 12

12a. Cervical spine well developed, sharp.............................go to 13
12b. Cervical spine lacking or indistinct.......Procambarus seminolae

 epic enop lito web

Figure 4. Left gonopods of male Procambarus epicyrtus, A) Form II, B) Form I; P. enoplosternum, C) Form II, D) Form I; P. litosternum E) Form II, F) Form I.  Modified from Hobbs (1981).

13a. Tip of gonopod bent caudally
(Figs. 4A, B)............................................Procambarus epicyrtus
13b. Tip of gonopod not bent caudally (Figs. 4C-F)............go to 14

14a. Rounded caudal knob
(Figs. 4C, D).....................................Procambarus enoplosternum
14b. Caudal knob narrow, linear
(Figs. 4E,F)............................................Procambarus litosternum

15a. Width of palm approximately equal to length of mesial margin of palm............................................................Procambarus barbatus
15b. Width of palm greater than 1.4 times as long as mesial margin
of palm...........................................................Cambarus latimanus

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