Common Name: Muckalee Crayfish
Scientific Name: Procambarus (Pennides) gibbus Hobbs
Rarity Ranks: G3/S3
State Legal Status: Threatened
Federal Legal Status: None
Description: The overall appearance of the Muckalee Crayfish is light to dark brown with dark markings. The claws are dark with whitish tubercles; the claws can be quite large on males in reproductive condition. The carapace typically has a dark saddle near its rear edge that extends forward on either side of the carapace as two “horns”. The most obvious pigmentation characteristics are the discrete reddish or purplish spots along the margins of the abdomen. The rostrum is long and sharply pointed and there are two distinctive cervical spines on either side of the carapace. Adult Muckalee Crayfish may reach a maximum total body length of over 100 mm (>4 in).
Similar Species: The presence of two cervical spines separates the Muckalee Crayfish from all Georgia species except other members of the subgenus Pennides. The White Tubercled Crayfish (Procambarus spiculifer) is very similar and occurs in the mainstem Flint River near the tributaries where Muckalee Crayfish live. Details of the male reproductive structure is required to separate these two species. All specimens resembling Muckalee Crayfish and White Tubercled Crayfish collected in the lower Flint River system should be examined carefully.
Habitat: The Muckalee 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 Muckalee 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 April and August and no females with eggs have been found. The smallest male breeding male is about 60 mm (2.4) in length (Hobbs 1981).
Survey Recommendations: Since this species is usually found in flowing water, it is most easily collected by holding a net perpendicular to the current downstream of vegetation or woody debris and kicking to dislodge and scare crayfish into the net. If there are rocks or logs in the creek, they may be carefully lifted and crayfish may be pinned by hand or coaxed into a dipnet. Using a backpack electroshocker or minnow traps can be effective as well. Collections in spring or fall are more likely to produce males in reproductive condition which can be helpful with identifications.
Range: The Muckalee Crayfish is only known from the Muckalee Creek system in the Lower Flint River drainage and Coolewahee Creek in Baker County (also Flint River trib.). Hobbs (1981) listed a single collection from a small tributary to the Flint River in Crawford County.
Threats: The small range size of this species makes it vulnerable to extirpation from the state. Of great concern is the presence of a non-native invasive species (Creole Painted Crayfish, Orconectes palmeri creolanus) that is established in the lower Flint River system. This species appears to be displacing the White Tubercled Crayfish in the Flint mainstem (Sargent et al. 2011) but has not yet been found in Muckalee or Coolewahee creeks. Since Muckalee Crayfish is very closely related to White Tubercled Crayfish, it seems likely that Muckalee Crayfish will be in jeopardy if the Creole Painted Crayfish is able to access Muckalee and Coolewahee Creeks.
Conservation and Management Recommendations: General watershed level protection measures will help secure the continued existence of the Muckalee 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.
Hobbs, H. H., Jr. 1981. The crayfishes of Georgia. Smithsonian Contributions to Zoology 318:1-549.
Sargent, L.W., S.W. Golladay, A.P. Covich, and S.P. Opsahl. 2011. Physicochemical
habitat association of a native and a non-native crayfish in the lower Flint River, Georgia: Implications for invasion success. Biological Invasions 13:499–511.
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: September 2012