genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
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 ...
native to western
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
(USA and Canada), containing six species, two of which are extinct:
*†'' Pacifastacus chenoderma'' (fossil:
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
–
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Pacifastacus connectens''
*'' Pacifastacus fortis'' –
Shasta crayfish
''Pacifastacus fortis'' (known as the Shasta crayfish or placid crayfish) is an endangered crayfish species endemism, endemic to Shasta County, California, where it is found and first described in 1914, only in isolated spots along the Pit River ...
Pacifastacus leniusculus
The signal crayfish (''Pacifastacus leniusculus'') is a species of crayfish indigenous to North America. Introduced to Europe in the 1960s to supplement the North European ''Astacus astacus'' fisheries, which were being damaged by crayfish plague ...
'' –
signal crayfish
The signal crayfish (''Pacifastacus leniusculus'') is a species of crayfish indigenous to North America. Introduced to Europe in the 1960s to supplement the North European ''Astacus astacus'' fisheries, which were being damaged by crayfish plague ...