The coldwater darter (''Etheostoma ditrema'') is a species of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or hor ...

, a darter from the

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Etheostomatinae Etheosomatidae is a species rich subfamily of freshwater ray-finned fish, the members of which are commonly known as the darters. The subfamily is part of the family Percidae which also includes the perches, ruffes and pikeperches. The family i ...

, part of the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Percidae The Percidae are a family of ray-finned fish, part of the order Perciformes, which are found in fresh and brackish waters of the Northern Hemisphere. The majority are Nearctic, but there are also Palearctic species. The family contains more than ...

, which also contains the

perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Percif ...

es, ruffes and pikeperches. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the United States, where it occurs in the

Coosa River The Coosa River is a tributary of the Alabama River in the U.S. states of Alabama and Georgia. The river is about long.U.S. Geological Survey. National Hydrography Dataset high-resolution flowline dataThe National Map, accessed April 27, 2011 ...

system of

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

Alabama (We dare defend our rights) , anthem = "Alabama (state song), Alabama" , image_map = Alabama in United States.svg , seat = Montgomery, Alabama, Montgomery , LargestCity = Huntsville, Alabama, Huntsville , LargestCounty = Baldwin County, Al ...

, and

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

Description

The coldwater darter has a dark brown back which is mottled and has nine saddle-like blotches which vary in resolution. The flanks have irregular brown mottling, and some individuals show darker centers which create horizontal lines, There are three spots arranged one on top of the other at the base of the

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

and there is usually a dark bar below the eye. The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

and

s are marked with dark spots on their rays, and these vary in extent on the rays of the remaining fins In breeding males, the color of the belly changes to scarlet and reddish spots develop on the flanks. The spiny part of the dorsal fin has a bluish ban on the margin and in the middle with red bands alternating with these. The soft-rayed portion of the dorsal fin is transparent but may show a slight bluish tinge and it has a row of reddish spots along the centre and the base. The

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

is bluish with a scattering of black and reddish spots along its base. The red and blue colours of the males are intensified during the

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...

season. The coldwater darter can reach a length of , though most only reach about .

Distribution

The coldwater darter is endemic to the Coosa River drainage covering the in the Ridge and Valley Province above the

Fall Line A fall line (or fall zone) is the area where an upland region and a coastal plain meet and is typically prominent where rivers cross it, with resulting rapids or waterfalls. The uplands are relatively hard crystalline basement rock, and the coa ...

in northeastern Alabama, northwestern Georgia, and the extreme southeast of Tennessee.

Habitat and ecology

The coldwater darter is restricted to pools and streams that are fed by springs and they are usually found among underwater vegetation in water less than a meter deep. Aquatic moss,

watercress Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family Brassicaceae. Watercress is a rapidly growing perennial plant native to Europe and Asia. It is one of the oldest known leaf ve ...

, and milfoil are common habitats for the coldwater darter, as they perch on the clumps of vegetation.

Taxonomy

The coldwater darter was first formally described in 1965 by John S. Ramsey and Royal Dallas Suttkus with the type locality given as a tributary of Mills Creek which is a tributary of the

Chattooga River The Chattooga River (also spelled Chatooga, Chatuga, and Chautaga, variant name Guinekelokee River) is the main tributary of the Tugaloo River. Water course The headwaters of the Chattooga River are located southwest of Cashiers, North Carolin ...

, west of

Lyerly, Georgia Lyerly is a town in Chattooga County, Georgia, United States. As of the 2020 census, the town had a population of 454. History A post office called Lyerly has been in operation since 1889, when a small town began to develop around a depot constru ...

. It is regarded as a member of the subgenus ''Oligocephalus'' and it is thought that its closest relative is the

Gulf darter The gulf darter (''Etheostoma swaini'') is a species of freshwater ray-finned fish, a darter from the subfamily Etheostomatinae, part of the family Percidae, which also contains the perches, ruffes and pikeperches. It is found in Louisiana, Miss ...

(''E. swaini''). There is also some evidence that this is a

species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

and it may be split into two or more species in future.

References

{{Taxonbar, from=Q304771 Freshwater fish of the United States Endemic fauna of the United States Etheostoma Fish described in 1965 Taxonomy articles created by Polbot