Two new crayfishes of the genus Cambarus (Decapoda: Cambaridae) from Northern Alabama and South Central Tennessee, U.S.A.

Multivariate and univariate statistical analyses of morphometric data and examination of morphological characters of the crayfish species Cambarus (Hiaticambarus) longirostris revealed the existence of two undescribed species from populations previously considered to be C. longirostris in tributaries of the Tennessee River in north Alabama and central south Tennessee. Cambarus (Hiaticambarus) andersoni and Cambarus (Hiaticambarus) diupalma differed from C. longirostris and from each other in aspects of chela morphometrics and in the presence or absence of qualitative characters. Cambarus andersoni has a corneous spine on the base of the ventral surface of the rostrum that is absent in the other two species; C. diupalma abdominal pleura are acute whereas they are subtruncate in C. andersoni and in C. longirostris. The known range of both of the new species is restricted to northern tributaries of the Tennessee River in south Tennessee and north Alabama. Cambarus diupalma is considered Endangered and C. andersoni is considered Vulnerable using American Fisheries Society conservation categorization.

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.