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 Oconee River System

1a. Two cervical spines (Fig. 1)..................Procambarus spiculifer
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. Crayfish entirely orange............................Cambarus truncatus
3b. Crayfish not entirely orange............................................go to 4

4a. Claw tubercles reddish or orangish..................................go to 5
4b. Claw tubercles not reddish or orangish............................go to 6

  howellae paeninsulanus clarkii

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

5a. Tip of male gonopod pointed (Fig. 2A)......Procambarus howellae
5b. Tip of male gonopod rounded (Fig 2B).........Procambarus clarkii

6a. Greatest width of palm less than length of mesial margin of palm (sometimes about equal in females).......................................go to 7
6b. Greatest width of palm greater than length of mesial margin of palm..................................................................................go to 12

7a. Dorsal surface of rostrum with dense
setae...........................................................Procambarus pubescens
7b. Dorsal surface of rostrum with at most, scattered setae....go to 8

8a. Upper sides of carapace with either discrete spots or  dark
line..........................................................................................go to 9
8b. Upper sides of carapace without discrete spots or dark line...................................................................Procambarus acutus

9a. Areola wide, averaging less than four times as long as wide...................................................Procambarus enoplosternum
9b. Areola narrower, averaging more than five times as long as
wide.....................................................................................go to 10

10a. Upper sides of carapace with two discrete
spots...........................................................Procambarus seminolae
10b. Upper sides of carapace with dark horizontal
line........................................................................Procambarus hayi

caritus pyg depress web

Figure 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).

11a. Mesial margin of palm with jagged, irregular tubercles (Figs. 3A,B)................................................................................go to 12
11b. Mesial margin of palm with similar sized tubercles
(Fig. 3C).............................................................................go to 13

caritus truculentus web

Figure 4. A-C, Procambarus caritus. A) annulus ventralis of female; B) gonopod of Form II male; C) gonopod of Form I male. D-F, Procambarus truculentus. D) annulus ventralis of female; E) gonopod of Form II male; F) gonopod of Form I male.

12a. Male gonopod hatchet shaped (Figs. 4E, F); female annulus ventralis without tubercles surrounding central depression
(Fig. 4D)..................................................Procambarus truculentus
12b. Male gonopod not hatchet shaped (Figs. 4B, C); female
annulus ventralis with tubercles surrounding central depression
(Fig. 4A)..........................................................Procambarus caritus

13a. Fingers of claw with black submarginal
pigment............................................................Orconectes juvenilis
13b. Fingers of claw without black submarginal pigment........go to 14

14a. One row of tubercles along mesial margin of palm..........go to 15
14b. More than one row of tubercles along mesial margin of
palm......................................................................................go to 16

15a. Color brown with darker mottling....Cambarus bartonii bartonii
15b. Color greenish to olive with red highlights......Cambarus howardi

striatus latimanus dorsal web

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

16a. 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
16b. 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

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