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Species Description

Broad River Burrowing Crayfish

Distocambarus (Distocambarus) devexus


Classification

Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Decapoda
Family: Cambaridae

Description

The Broad River Burrowing Crayfish is pale tan to brown in color and its carapace is marked with dark brown to black spots. The 1 st abdominal segment is decorated with dark, rectangular spots. These spots become lighter and smaller on the other abdominal segments. The telson (middle portion of the tail) has paired dark patches. The long, narrow chelae (claws) are covered with tubercles (small bumps). The eyes of this crayfish are small and its rostrum lacks spines and tubercles. The areola is narrow and adorned with 2-3 spots in the narrowest portion. The carapace usually measures less than 37 mm (1.45 in) in length. The Broad River Burrowing Crayfish has a total body length that often measures less than 70 mm (2.8 in).

Life Cycle

There have been relatively few life history studies conducted on crayfish. The available life history data for Distocambarus devexus is limited to the form or condition of specimens collected during certain times of the year. First-form (sexually mature) males have been collected during April. There is little information regarding the specific details of the life cycle of the Broad River Burrowing Crayfish, but its life cycle is presumably fairly similar to the generalized crayfish life history described below. Copulation involves a sexually mature male crayfish grabbing a female and depositing sperm packages (spermatophores) into the seminal receptacle on the abdomen of a receptive female crayfish. Females secrete a sticky substance on the underside of their abdomen and pleopods in order to attach their eggs. The eggs and sperm (from the seminal receptacle) are then released upon the sticky surface and fertilization occurs. Based upon the size of various specimens collected at different times of the year, there is speculation that females lay eggs during the late spring and early summer. A female carrying eggs on her abdomen and legs is said to be "in berry." Embryos develop and hatch on the underside of females in 2-20 weeks, likely depending upon species and temperature. The immature hatchlings molt (shed their exoskeleton to allow growth) and remain attached to their mother. These first-stage immature crayfish look fairly similar to typical crayfish, but have disproportionately large heads and eyes. Another molting takes place in about 1-2 weeks. These second-stage immature crayfish look even more like adult crayfish. Second-stage or third-stage immature crayfish leave their mother's surface and become independent. These young crayfish continue molting and growing and are usually sexually mature by their second or third autumn. Many adult crayfish die within 3 years of hatching.

Natural History

backwards into their burrows.

Range

This species is found within Broad River drainage areas of Elbert, Oglethorpe and Wilkes counties in Georgia . Adults construct complex burrows in floodplain areas that are usually marked with poorly constructed chimneys.

Conservation Status

The Broad River Burrowing Crayfish is listed as Rare in Georgia . It has a restricted range and very small population size. Destruction of its habitat (floodplain areas with sandy-clay soil) is likely the most immediate threat to this species.

Similar Species

Cambarus latimanus is the species that is most likely to be confused with the Broad River Burrowing Crayfish. C. latimanus, however, has larger eyes and a dark olive/greenish gray or brownish olive and orange appearance. Identification of the rare Broad River Burrowing Crayfish should usually be verified by a trained individual.