Common Name: DISJUNCT CRAYFISH
Scientific Name: Procambarus (Pennides) raneyi Hobbs
Rarity Ranks: G4/S4
State Legal Status: None
Federal Legal Status: NoneDescription: 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 has 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).
Similar Species: The presence of two cervical spines separates the Disjunct Crayfish from all Georgia species except other members of the subgenus Pennides. 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.
Habitat: 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.
Diet: 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.
Life History: 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).
Survey Recommendations: 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. Collections in spring or fall are more likely to produce males in reproductive condition which can be helpful with identifications.
Range: 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.
Threats: This species is considered secure.
Conservation and Management Recommendations: General watershed level protection measures will help secure the continued existence of the variable 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 Jones, D. R. 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(8):372-389.
Date Compiled or Updated: August 2012