genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
crayfish
Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...
native to western
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
(USA and Canada), containing six species, two of which are extinct:
*†'' Pacifastacus chenoderma'' (fossil:
Miocene
The Miocene ( ) is the first 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 means "less recen ...
–
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Pacifastacus connectens''
*''
Pacifastacus fortis
''Pacifastacus fortis'' (known as the Shasta crayfish or placid crayfish) is an endangered crayfish species endemic to Shasta County, California, where it is found only in isolated spots on the Pit River and Fall River Mills. The exact subpopulat ...
'' –
Shasta crayfish
''Pacifastacus fortis'' (known as the Shasta crayfish or placid crayfish) is an endangered crayfish species endemic to Shasta County, California, where it is found only in isolated spots on the Pit River and Fall River Mills. The exact subpopulat ...
Pacifastacus leniusculus
The signal crayfish (''Pacifastacus leniusculus'') is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the North European ''Astacus astacus'' fisheries, which were being damaged by crayfish plague, bu ...
'' –
signal crayfish
The signal crayfish (''Pacifastacus leniusculus'') is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the North European ''Astacus astacus'' fisheries, which were being damaged by crayfish plague, but ...