Two new species of burrowing crayfish in the genus Lacunicambarus (Decapoda: Cambaridae) from Alabama and Mississippi.

While sampling for the Rusty Gravedigger, Lacunicambarus miltus, Taylor et al. (2011) found one or more potentially undescribed burrowing crayfish species in the genus Lacunicambarus inhabiting the area between the Pascagoula River and Mobile Bay in southern Alabama and Mississippi. Molecular analyses by Glon et al. (2018) confirmed that samples from this area were genetically distinct from other Lacunicambarus crayfishes. These findings prompted a dedicated sampling trip in January 2020. We used morphological and molecular analyses to investigate the specimens we collected and, based on our results, we describe two new crayfish species: the Lonesome Gravedigger, L. mobilensis sp. nov. and the Banded Mudbug, L. freudensteini sp. nov. Lacunicambarus mobilensis sp. nov. is sister to the Rusty Gravedigger, L. miltus, while L. freudensteini sp. nov. is sister to the Painted Devil Crayfish, L. ludovicianus. Both new species are currently known from a small number of sites in southern Alabama and Mississippi and may require conservation attention. In addition, we provide an updated key to Lacunicambarus crayfishes that includes these new species.

Review of crayfish color patterns in the Family Cambaridae (Astacoidea), with discussion of their possible importance.

The use of color photographs in crayfish species descriptions, state faunal books and popular articles is relatively recent. Except for verbal color descriptions, color and color patterns have not often been explored by crayfish researchers. Carotenoids and carotenoproteins are responsible for much of the color found in the integument and exoskeleton of crayfishes and other crustaceans. Research has shown variation in color may be the result of the environment, diet, molt stage and age, genetics, or a combination of these. Crayfishes possess color vision, may use polarization vision, and have the possibility of fluorescent vision. They also have very good low light vision. Crayfishes have a multichromatic range in color sensitivity; it ranges from blue to red, with no UV sensitivity. Color vision may be an important factor in intraspecific and interspecific competition, territoriality, camouflage, sexual selection, and communication. A distinction is made between base or background colors displayed in crayfishes and their exhibited color patterns. While actual base or background colors may vary among individual crayfishes, a case is made that color patterns show much less intraspecific variation. Distinct color patterns are the result of highly contrasting colors on appendages or parts of appendages such as chelae, leg joints, tail fan, spines, and tubercles. Body regions like the carapace and abdomen may also have contrasting spots, bands or stripes. Color patterns may be useful in better understanding crayfish taxonomy, phylogeny, and evolutionary convergence, and examples are provided.

A new dwarf crayfish (Decapoda: Cambaridae) from floodplain swamps in central Alabama.

Cambarellus (Pandicambarus) rotatus, new species, is a dwarf crayfish from floodplain swamps in the Tombigbee and Black Warrior river drainages of Greene, Hale, and Marengo counties, Alabama. The new species is morphologically most similar to Cambarellus (Pandicambarus) lesliei. They differ in a several morphological characters. Cambarellus rotatus, new species, has gonopods that are rotated mesially so that the terminal elements oppose each other, and they have a short C-shaped sperm groove. These are unique features among known species of Cambarellus.

A new species of crayfish in the genus Orconectes (Decapoda: Cambaridae) from the Tennessee River Drainage with comments on and key to members of the O. juvenilis Species Complex.

The crayfish subgenus Procericambarus (genus Orconectes) found in the Eastern Highlands of the United States represents a rich assemblage of stream-dwelling macroinvertebrates. While the taxonomic status and distribution of its members were clarified in a previous study, newly diagnosed characters and newly collected specimens warranted a revision to previous hypotheses of Procericambarus membership in the southeastern United States. Using morphological characters, we describe herein a new species of crayfish occurring in the Tennessee River drainage of northern Alabama and southwestern Tennessee. We also provide a revised key for the identification of members of O. juvenilis Species Complex.

Cambarus (Depressicambarus) clairitae, a new species of crayfish (Decapoda: Cambaridae) from Alabama with a review of the halli Group in the subgenus Depressicambarus.

Cambarus (Depressicambarus) clairitae, new species, is an epigean crayfish from two drainages of the Locust Fork system in Blount and Jefferson counties, Alabama. It belongs to the halli Group in the subgenus Depressicambarus. The new species is morphologically most similar to Cambarus (Depressicambarus) englishi. They differ in a several morphological characters. Cambarus englishi has a more strongly recurved central projection, a wider areola, and a more distinct and set off rostral acumen than the new species. It also has light gray to white antennae while the antennae of the new species are brown. In addition to the description of the new species, the halli Group in Alabama is discussed.

Procambarus (Girardiella) holifieldi, a new species of crayfish (Decapoda: Cambaridae) from Alabama with a revision of the Hagenianus Group in the subgenus Girardiella.

Procambarus (Girardiella) holifieldi, new species, is a primary burrowing crayfish from a low-lying field in Perry County, Alabama. It belongs to the Hagenianus Group in the subgenus Girardiella.  The new species is morphologically most similar to Procambarus (Girardiella) barbiger.  They differ in the size and shape of the caudal processes.  Procambarus barbiger has a beard along the mesial margin of the palm of the chela, while the new species lacks the beard.  In addition to the description of the new species, the Hagenianus Group is reviewed and new synonymies are provided. We demonstrate that a cephalic process is indeed present in the Hagenianus Group.

Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea).

Rates of biodiversity loss are higher in freshwater ecosystems than in most terrestrial or marine ecosystems, making freshwater conservation a priority. However, prioritization methods are impeded by insufficient knowledge on the distribution and conservation status of freshwater taxa, particularly invertebrates. We evaluated the extinction risk of the world's 590 freshwater crayfish species using the IUCN Categories and Criteria and found 32% of all species are threatened with extinction. The level of extinction risk differed between families, with proportionally more threatened species in the Parastacidae and Astacidae than in the Cambaridae. Four described species were Extinct and 21% were assessed as Data Deficient. There was geographical variation in the dominant threats affecting the main centres of crayfish diversity. The majority of threatened US and Mexican species face threats associated with urban development, pollution, damming and water management. Conversely, the majority of Australian threatened species are affected by climate change, harvesting, agriculture and invasive species. Only a small proportion of crayfish are found within the boundaries of protected areas, suggesting that alternative means of long-term protection will be required. Our study highlights many of the significant challenges yet to come for freshwater biodiversity unless conservation planning shifts from a reactive to proactive approach.