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Procambarus

Procambarus is a genus of crayfish in the family Cambaridae, all native to North and Central America. It includes a number of troglobitic species, and the marbled crayfish (marmorkrebs), which is parthenogenetic. Originally described as a subgenus for four species, it now contains around 161 species.

Biogeography

The majority of the diversity is found in the southeastern United States, but the genus extends as far south as Guatemala and Honduras, and on the Caribbean island of Cuba. After United States, the highest diversity is in Mexico with about 45 species. Only two are native to Guatemala (P. pilosimanus and P. williamsoni), one to Belize (P. pilosimanus), one to Honduras (P. williamsoni) and three to Cuba (P. atkinsoni, P. cubensis and P. niveus).

Subgenus Ortmannicus was the most widespread, with the range of Procambarus acutus extending as far north as the Great Lakes and New England, as well as south into northeastern Mexico; the subgenus Girardella also extended from the Great Lakes to Mexico, but was distributed further west than Ortmannicus. Scapulicambarus and Pennides were widespread in the southeastern United States, further west (Texas and Louisiana) than Leconticambarus which was centered on Florida and neighbouring states. The subgenus Austrocambarus had the most southerly distribution, being found in Cuba and parts of Central America from Mexico to Belize, Guatemala and Honduras. The other subgenera are more restricted in their distributions, including three endemic to central Mexico, and six endemic to small areas in the United States.

A few species of Procambarus have been introduced to regions outside their native range, both in North America and other continents. They are frequently categorized as invasive species, representing a threat to natives, including rarer crayfish species.

The earliest known fossil member of the genus is Procambarus primaevus, known from the Early Eocene-aged deposits of Fossil Butte in the Green River Formation in Wyoming, USA. This suggests that during the Eocene, Procambarus was found as far west as the Intermountain West of the United States, where it is no longer present today.

Description

Procambarus can be distinguished from other genera of crayfish by the form of the first pleopod in males, which typically has three or more processes at the tip, compared to two or fewer in Faxonius and Cambarus.

Ecology

Most Procambarus species live in various above-ground waters such as rivers, streams, lakes, ponds and swamps, but several are troglobitic, living in caves, particularly in karstic areas. In the United States, these include both species in subgenus Lonnbergius (P. acherontis and P. morrisi). Other cave-dwellers in the United States with various levels of troglomorphic adaptions are P. attiguus, P. erythrops, P. franzi, P. leitheuseri, P. lucifugus, P. milleri and P. orcinus, but these are all members of subgenera that also include species from above-ground waters. In Cuba, P. niveus is a cave-dweller. In Mexico, many species have been recorded in caves, but most of these have also been recorded from above-ground waters; only P. cavernicola, P. oaxacae, P. rodriguezi and P. xilitlae are strict cave-dwellers and troglomorphic. In 2007, troglomorphic specimens of P. clarkii were found in caves in Portugal and Italy.

Taxonomy

Procambarus was originally described by Arnold Edward Ortmann in 1905 as a subgenus of a wider genus Cambarus, and originally contained only four species (P. williamsoni, P. digueti, P. mexicanus and P. cubensis). The subgenus was elevated in 1942 to the taxonomic rank of genus by Horton H. Hobbs Jr., who later erected most of the subgenera formerly recognized within the genus in a 1972 monograph. However, more recently, the subgenera have been eliminated, and while it is recognized that Procambarus is not monophyletic, later literature does not make further taxonomic changes, instead suggesting that more species sampling is required.

Species

Notes

References

External links