Cambarus bartonii is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of crayfish

Crayfish

Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...

 native to eastern North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

, where it is called the common crayfish or Appalachian brook crayfish.

C. bartonii was the first crayfish to be described from North America, when Johan Christian Fabricius

Johan Christian Fabricius

Johan Christian Fabricius was a Danish zoologist, specialising in "Insecta", which at that time included all arthropods: insects, arachnids, crustaceans and others...

 published it under the name Astacus Bartonii in his 1798 work Supplementum entomologiae systematicae. The locality where his specimen was captured is not known, but is thought to be near Philadelphia, Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

.

C. bartonii lives in fast–flowing, cool, rocky streams as well as shallow lakes, and is found in the Canadian provinces

Provinces and territories of Canada

The provinces and territories of Canada combine to make up the world's second-largest country by area. There are ten provinces and three territories...

 of Ontario

Ontario

Ontario is a province of Canada, located in east-central Canada. It is Canada's most populous province and second largest in total area. It is home to the nation's most populous city, Toronto, and the nation's capital, Ottawa....

, Quebec

Quebec

Quebec or is a province in east-central Canada. It is the only Canadian province with a predominantly French-speaking population and the only one whose sole official language is French at the provincial level....

 and New Brunswick

New Brunswick

New Brunswick is one of Canada's three Maritime provinces and is the only province in the federation that is constitutionally bilingual . The provincial capital is Fredericton and Saint John is the most populous city. Greater Moncton is the largest Census Metropolitan Area...

, and in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 from Maine

Maine

Maine is a state in the New England region of the northeastern United States, bordered by the Atlantic Ocean to the east and south, New Hampshire to the west, and the Canadian provinces of Quebec to the northwest and New Brunswick to the northeast. Maine is both the northernmost and easternmost...

 to Alabama

Alabama

Alabama is a state located in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama ranks 30th in total land area and ranks second in the size of its inland...

. In the south of its range, C. bartoni is restricted to the Appalachian Mountains

Appalachian Mountains

The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...

 and their foothills.

Colouration is usually plain dark brown, although mottling is occasionally seen, as is a saddle

Saddle

A saddle is a supportive structure for a rider or other load, fastened to an animal's back by a girth. The most common type is the equestrian saddle designed for a horse, but specialized saddles have been created for camels and other creatures...

-shaped marking.

Several subspecies of C. bartonii have been recognised, but it is unclear how advisable this is, and work is ongoing to determine patterns of infraspecific variation.

Cambarus bartonii is included as a species of Least Concern

Least Concern

Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...

 on the IUCN Red List

IUCN Red List

The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...

.