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Procambarus raneyi Hobbs, 1953
Disjunct Crayfish
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G4
State Rank: S4
Element Locations Tracked in Biotics: No
SWAP 2015 Species of Greatest Conservation Need (SGCN): No
SWAP 2025 Species of Greatest Conservation Need (SGCN): No
2025 SGCN Priority Tier: None
Element Occurrences (EOs) in Georgia: 0
Habitat Summary for element in Georgia: Georgia habitat information not available
The overall appearance of the Disjunct Crayfish is tan to brownish with darker markings. The carapace may have a dark saddle near its rear edge that extends forward on either side of the carapace as two “horns”. The sides of the abdomen have a brownish striped appearance. The palms of the claws are brown with dark tubercles and the fingers appear darker; they are black in larger individuals. The areola is wide and the rostrum is long and sharply pointed with marginal spines; there are two distinctive cervical spines on either side of the carapace. Adult Disjunct Crayfish may reach a maximum total body length of over 100 mm (>4 in).
The presence of two cervical spines separates the Disjunct Crayfish from all Georgia species except other crayfish formerly placed in the subgenus Pennides (total of 5 species). The fairly similar White Tubercled Crayfish, Procambarus spiculifer can occur with this species in the Broad and Ocmulgee river systems. However, the palms of the White Tubercled Crayfish are dark (blackish) with white tubercles rather than light brown with dark tubercles. There are also differences in the male reproductive structure which must be examined using magnification.
The Disjunct Crayfish is found in a wide array of flowing water habitats across its range. Depending on the substrates available it can be found hiding beneath rocks, within woody debris or leaf litter, and beneath undercut banks.
No studies of the Disjunct Crayfish diet are known. Crayfishes are considered opportunistic omnivores and likely feed on live and decaying vegetation, aquatic insect larvae, small fishes, and dead animal matter.
Stream dwelling crayfishes typically hide during the day and come out at night to feed. Reproduction usually occurs during the spring and fall, but males in reproductive condition may be found at any time during the year. When female crayfish are ready to lay eggs, they usually find a secure hiding place and hence are rarely encountered. When the eggs are released, the female attaches them to her swimmerets and is said to be “in berry.” Upon hatching, the juvenile crayfish are attached to the mother by a thread. After the juveniles molt for the second time, they are free of the mother, but stay close and will hold on to her for some time. Eventually they move off on their own. Crayfishes molt 6 or 7 times during their first year of life and most are probably able to reproduce by the end of that year. Males in reproductive condition have been collected in March, April, May, June, September, October, and November. Two females with eggs were found in South Carolina in April (Hobbs 1981). The smallest male in reproductive condition is about 74 mm (2.9) and the smallest female with eggs about 85 mm (3.3) in length (Hobbs 1981).
In rocky streams, most easily collected by holding a net perpendicular to the current downstream of a large rock, then lifting the rock and disturbing the substrate beneath it. If a crayfish is hiding underneath the rock, it will likely move into the net. Use the same technique in streams with woody debris or aquatic plants. Shocking downstream into a seine net with a backpack electroshocker is also effective. Setting baited minnow traps overnight would likely yield specimens as well.
As the name implies, the Disjunct Crayfish has a discontinuous distribution. It is found from the Ocmulgee River system in Georgia, east to the North Fork Edisto and upper Broad river systems in South Carolina (Eversole and Jones 2004, Hobbs 1981). In Georgia is found in the Ocmulgee and Savannah river systems but is absent from the Oconee River system which lies between them.
This species is threatened in Georgia by land uses within its range that could alter hydrology and water quality. Introduction of non-native species is a threat to all native crayfishes.
This species is common and widespread in Georgia and is thus considered secure.
General watershed level protection measures will help secure the continued existence of the Disjunct Crayfish in Georgia. These include the protection of riparian zones, control of sediment and nutrient runoff from farms and construction sites, and limiting the amount of impervious cover (e.g., pavement) within occupied watersheds. Non-native crayfishes should never be used for bait. Instead, anglers should use crayfishes collected from the river system they will be fishing in and should never release unused bait crayfish back into Georgia waters.
Eversole, A.G., and D.R. Jones. 2004. Key to the crayfish of South Carolina. Clemson University, Clemson, SC. 43 pp.
Hobbs, H.H., Jr. 1981. The crayfishes of Georgia. Smithsonian Contributions to Zoology 318:1–549.
Taylor, C.A., G.A. Schuster, J.E. Cooper, R.J. DiStefano, A.G. Eversole, P. Hamr, H.H. Hobbs III, H.W. Robison, C.E. Skelton, and R.F. Thoma. 2007. A reassessment of the conservation status of crayfishes of the United States and Canada after 10+ years of increased awareness. Fisheries 32:372–389.
Christopher E. Skelton
C. Skelton, August 2012: original account
C. Skelton, March 2019: general update of account.
D.Weiler, September 2019: photo added