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Sickle darter
The sickle darter (''Percina williamsi'') is a recently identified species closely related to a well-known darter, ''Percina macrocephala''.〔Near,Thomas J. & Page,Lawrence M. 2007. A New Darter from the Upper Tennessee River Drainage Related to ''Percina macrophala'' (Percidae: Etheostomatinae) Copeia 3:605-613. http://www.eeb.yale.edu/near/33.pdf.〕 Discovered in 2007 in the upper Tennessee River drainage, the sickle darter is a small (around 90.5 mm),slender bodied, freshwater and benthopelagic fish that most likely feeds on small crayfish and mayflies since it shares a large mouth and long snout with its sister species . The known distribution of the sickle darter is the upper drainage of the Tennessee River of Tennessee, North Carolina and Virginia. It is distinguished from all other ''Percina'' darters except its sister species ''P. macrocephala'' by a dark suborbital bar and a black bar subtending a medial black spot on the base of the caudal fin.〔Redescription, Distribution, Variation and Life History Notes on Percina macrocephala (Percidae), Lawrence M. Page, Copeia , Vol. 1978, No. 4 (Dec. 28, 1978), pp. 655-664.〕 It stays in mostly rocky, sandy, or silty substrates in clear creeks or small rivers in the Appalachian Mountains. The sickle darter spawns in late winter in gravel shoals. It also has large scales which make it different from ''macrocephala''.〔Heckman, K.L., Near, T.J. & Alonzo, S.H. 2009. Phylogenetic relationships among Boleosoma darter species (Percidae: Etheostoma). Molecular Phylogenetics and Evolution 53: 249–257.
http://www.yale.edu/eeb/near/48_Heckman_et_al2009.pdf.〕 It’s known to be extirpated from most of its home habitat mainly because of agricultural practices that cause siltation and turbidity which causes most populations of the sickle darter to be widely scattered. But where it is found, it can be observed with regularity. Taking all this into consideration, the sickle darter does not have a formal conservation status under any federal or state law although its closely related species is considered a species of concern by the TWRA. Future management plans should include finding more locations of the sickle darter and decreasing further habitat destruction in known distributions by stating it as a fish of concern by state law.
==Geographic distribution==
As of right now the sickle darter has been found mostly in the upper Tennessee River drainage of Tennessee, Virginia, and North Carolina. It has also been caught in the French Broad System of Tennessee and Virginia, the Emory River in Tennessee, the Holston and Clinch Rivers of Tennessee and Virginia and low densities in the Little River in Blount County Tennessee.〔
Shute, P. W., & G. Hammerson. 2008. Sickle Darter ''Percina williamsi''. http://www.cumberlandhcp.org/files/natureserve/Fish_10.23.08/Sickle_Darter_10.13.08.pdf.〕 The largest specimen of the sickle darter was found in the Holston River with a length of 90.5 mm. Due to this distribution, they are considered a subtropical fish.〔2007. Sickle darter (Percina williamsi) fish profile. http://www.guppies.za.net/sickle-darter-percina-williamsi-fish-profile.aspx.〕 Before 2007, the sickle darter was considered to be part of the species of longhead darter (''Percina macrocephala'') so it has been recently classified as a new species of fish of which not much information has been found. They can be seen regularly in their inhabited rivers but outside of them and in between their distributions you would be hard pressed to find a sickle darter. This is most likely due to agricultural, municipal, and industrial practices casing siltation and increased turbidity which is a human made enemy of this darter.
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