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 161 species in 16 subgenera.
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.[2][3] 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).[3]
Subgenus Ortmannicus is 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 extends from the Great Lakes to Mexico, but is distributed further west than Ortmannicus.[4] Scapulicambarus and Pennides are widespread in the southeastern United States, where Remoticambarus also lives, further west (Texas and Louisiana) than Leconticambarus which is centered on Florida and neighboring states. The subgenus Austrocambarus has 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.[2][3][4]
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.[3][5][6]
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 Orconectes and Cambarus.[7]
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) and the single species in the subgenus Remoticambarus, P. pecki.[8] 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.[9]