Etheostoma percnurum
Encyclopedia
Etheostoma percnurum is a rare species of fish in the perch family
Percidae
The Percidae are a family of perciform fish found in fresh and brackish waters of the Northern Hemisphere. The family contains about 200 species in ten genera...

 known by the common name duskytail darter. It is native to Kentucky
Kentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...

, Tennessee
Tennessee
Tennessee is a U.S. state located in the Southeastern United States. It has a population of 6,346,105, making it the nation's 17th-largest state by population, and covers , making it the 36th-largest by total land area...

, and Virginia
Virginia
The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

 in the United States, where it occurs in the drainages of the Cumberland
Cumberland River
The Cumberland River is a waterway in the Southern United States. It is long. It starts in Harlan County in far southeastern Kentucky between Pine and Cumberland mountains, flows through southern Kentucky, crosses into northern Tennessee, and then curves back up into western Kentucky before...

 and Tennessee River
Tennessee River
The Tennessee River is the largest tributary of the Ohio River. It is approximately 652 miles long and is located in the southeastern United States in the Tennessee Valley. The river was once popularly known as the Cherokee River, among other names...

s. It was federally listed as an endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...

 of the United States in 1993, shortly before it was formally described as a new species.

E. percnurum is now considered a species complex
Species complex
A species complex is a group of closely related species, where the exact demarcation between species is often unclear or cryptic owing to their recent and usually still incomplete reproductive isolation. Ring species, superspecies and cryptic species complex are example of species complex...

. In 2008, examination of the morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

 of the fish led researchers to divide it into four species, describing the Citico darter
Etheostoma sitikuense
The common name of Etheostoma sitikuense is the Citico darter. It is one of the 324 fish species found in Tennessee....

 (Etheostoma sitikuense), the marbled darter
Etheostoma marmorpinnum
The common name of Etheostoma marmorpinnum is the marbled darter. It is one of the 324 fish species found in Tennessee....

 (Etheostoma marmorpinnum), and the tuxedo darter
Etheostoma lemniscatum
The common name of Etheostoma lemniscatum is the tuxedo darter. It is one of the 324 fish species found in Tennessee....

 (Etheostoma lemniscatum) as new. Because E. percnurum carries the endangered species status, the three new species may be given that status.

These fish are threatened by the impoundment of waterways, increased silt
Silt
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...

, logging
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...

, coal mining
Coal mining
The goal of coal mining is to obtain coal from the ground. Coal is valued for its energy content, and since the 1880s has been widely used to generate electricity. Steel and cement industries use coal as a fuel for extraction of iron from iron ore and for cement production. In the United States,...

, pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

, and disease.

External links

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