''Cambarus gentryi'', the linear cobalt crayfish, is a small species of burrowing

crayfish Crayfish are freshwater crustaceans belonging to the infraorder Astacidea, which also contains lobsters. Taxonomically, they are members of the superfamilies Astacoidea and Parastacoidea. They breathe through feather-like gills. Some spe ...

. One of 115 species in the genus Cambarus'','' it is notable for its deep blue

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

. It is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

Tennessee Tennessee (, ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders Kentucky to the north, Virginia to the northeast, North Carolina t ...

in the United States.

Taxonomy and description

Although three specimens of ''C. gentryi'' were collected and stored in the 1890s, the species was not described until 1970 by Horton Hobbs, Jr. This followed its 1968 collection by Dr. Glenn Gentry, from which the species name was derived.

Geographic range

The linear cobalt crayfish has been found in the Cumberland and Duck river basins in Tennessee.There are 37 reported sightings of ''C. gentryi'' on the Global Biodiversity Information Facility (GBIF) between 1962-2022. They are all localized to the southern part of

in the

USA The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous ...

, North America.

Physical description

''Cambarus gentryi'' has a shell length of around and pincers about long. Its shell is cobalt blue in colour with orange or yellow to yellowish-green markings. The eyes are small and well-developed, and the areola (a structure which runs along the centre of the

cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...

) is sublinear, or mostly uncurved. Like other

decapods The Decapoda or decapods, from Ancient Greek δεκάς (''dekás''), meaning "ten", and πούς (''poús''), meaning "foot", is a large order (biology), order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfis ...

, ''C. gentryi'' has ten pairs of legs, of which the forward-most pair are modified into robust pincers known as chela. The type specimen is stored in the Smithsonian Institution in Washington, D.C., USA under the identifier USNM 130283. The allotype (female) and morphotype (male) are in the same institution under the identifiers USNM 130284 and 130285.

Habitat

The linear cobalt crayfish creates burrows in damp areas along river banks. Its burrows have been described in several locations across its range; although sometimes limited by soil depth, they can have multiple openings to the surface and have been found to be up to about 2.5 m (8 ft) in length and in depth.

Development and reproduction

Adults in family Cambaridae alternate molts between reproductive (form I) and non reproductive (Form II) forms. Male form I has larger claws and altered sperm transfer gonopods; in some species, the female form I has a wider abdomen. On collection of ''C. gentryi'' specimens in and prior to 1970, first-form males were collected at various times of year (April, May, and November) and egg- or young-bearing females had not been collected or identified.

Lifespan

The exact lifespan of ''C. gentryi'' is not known; however, other individuals in this family (Cambaridae) have been known to live 6-7 years.

Ecological Interactions

''C. gentryi'' is a known host of ''Uncinocythere zancla'', an entocytherid osctracod. This is a small crustacean which lives as an obligate ectosymbiont to other crustaceans by attaching to the carapaces.

Conservation status

''Cambarus gentryi'' is listed as least concern by the IUCN.

Genomic information

Five publicly available gene fragment sequences exist for ''C. gentryi,'' available through NCBI genbank with taxonomy ID NCBI:txid318489. The following gene fragments are available: # Isolate JF2508 cytochrome c oxidase subunit I (COI) gene; Accession no. KX417101.1 # Histone H3 (H3) gene, partial cds; Accession no. DQ411804.1 # Cytochrome oxidase subunit I (CO1) gene, partial cds; mitochondrial; Accession no. DQ411785.1 # 12S ribosomal RNA gene, partial sequence; mitochondrial; Accession no. DQ411731.1 # 16S ribosomal RNA gene, partial sequence; mitochondrial; Accession no. AY853664.1

References

Cambaridae Endemic crustaceans of the United States Crustaceans described in 1970 Freshwater crustaceans of North America Endemic fauna of Tennessee Taxa named by Horton H. Hobbs Jr. {{Crayfish-stub