''Nothonotus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, 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 botanical subfamily names with "-oideae", and zo ...

Etheostomatinae Etheostomatinae 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 ...

, part of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

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 nearly 250 ...

, which also contains the

perch Perch is a common name for freshwater fish from the genus ''Perca'', which belongs to the family Percidae of the large order Perciformes. The name comes from , meaning the type species of this genus, the European perch (''P. fluviatilis'') ...

es, ruffes and pikeperches. It is

endemic Endemism is the state of a species being found only 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 foun ...

to the southeastern

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. First proposed as a sub-genus of ''

Etheostoma ''Etheostoma'' is a genus of small freshwater fish in the family (biology), family Percidae, and within the sub-family ''Etheostomatinae'', native to North America. Most are restricted to the United States, but species are also found in Canada and ...

'' in 1988, there is still debate regarding the appropriate taxonomic rank of ''Nothonotus'' in the literature .

Darter The darters, anhingas, or snakebirds are mainly tropical waterbirds in the family Anhingidae, which contains a single genus, ''Anhinga''. There are four living species, three of which are very common and widespread while the fourth is rarer and c ...

species comprise more than 180 of the

taxa.

''Nothonotus'' species

*FishBase lists the following four species: ** '' Nothonotus aquali'' (Coppercheek darter) ** '' Nothonotus microlepidus'' (Smallscale darter) ** '' Nothonotus sanguifluus'' (Bloodfin darter) ** '' Nothonotus starnesi'' (Caney fork darter) *Thomas Near and colleagues also included the following, which, where they are described at all in this treatment, are listed under ''

''. ** '' N. acuticeps'' ** '' N. bellus'' ** '' N. camurus'' ** '' N. chlorobranchius'' ** '' N. chuckwachattee'' ** '' N. denoncourti'' ** '' N. douglasi'' ** '' N. etowahae ** '' N. jordani'' ** '' N. juliae'' ** '' N. maculatus'' ** '' N. moorei'' ** '' N. rubrus'' ** '' N. rufilineatus'' ** '' N. tippecanoe'' ** '' N. vulneratus'' ** '' N. wapiti''

Phylogenetics

Members of the ''Nothonotus'' subspecies last shared a common ancestor approximately 18.5 MYA. Frequent hybridization, the rich diversity of the subgenus, and the limitations of the fossil record complicate phylogenetic assessments, which have not been fully resolved. Various conflicting relationships have been proposed using morphological characters, allozyme analysis, microsatellites, and mtDNA sequencing.

Life history

''Nothonotus'' darters are native to the riffle domains of highly graded drainages in North America. ''Nothonotus'' species vary in locality preference, but are known to cooccur in several drainages in the Eastern United States. ''Nothonotus'' darters engage in three reproductive strategies: egg burial, egg guarding, and egg tending, strategies hypothesized to have evolved multiple times. Most species have limited mobility, moving approximately 33–100 meters per year. They are restricted to suitable breeding and feeding grounds, making novel niche exploration rare, particularly in fast flowing drainages. Low mobility is hypothesized to have facilitated speciation in regions where multiple species appear to have historical sympatric distributions. Various life history traits like body size determine the niche range available to a particular species. The biogeographic dispersal model has been proposed as the most likely explanation of diversification and speciation of the subgenera. It has also been postulated that speciation occurred following niche partitioning, in response to competition where distributions overlap.

Anthropogenic influences and conservation implications

The low mobility and habitat specialization associated with the subgenus make ''Nothonotus'' species particularly sensitive to habitat degradation. Darter populations are frequently assessed as a proxy for stream habitat quality. In a comparative species richness survey, museum specimen from 1948–1955 contained approximately 33% more diversity than samples collected from 2005–2006 in the same localities despite more intensive sampling efforts in contemporary populations. The following ''Nothonotus'' species have been designated conservation statuses by IUCN redlist: Vulnerable : ''N. maculatum, N. acuticeps'', ''N. denoncourti, N. etowahae, N. wapiti''; Near threatened: ''N. aquali'', ''N. tippecanoe''; Endangered: ''N. moorei'', ''N. rubrum''. Impoundment by dams and siltation restrict gene flow between previously continuous populations, threatening the genetic diversity of various ''Nothonotus'' species. Siltation has been cited as the most concerning mode of

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

in aquatic habitats. Sediment issues occur when anthropogenic activities like mining, deforestation, urbanization, and road construction alter flow regimes and erosion rates. Genetic diversity assessments of ''Nothonotus'' populations are often conducted to determine the consequences of siltation on aquatic communities. Coloration, particularly conspicuous in males, is hypothesized to have evolved in response to sexual selection and habitat preference. Species residing higher in the water column, in clear water, and in habitats with low predation typically express stronger nuptial coloration patterns. Sedimentation may also interfere with mate identification due to reduced water clarity.

References

{{Taxonbar, from=Q15627790 Etheostomatinae Perciformes genera Taxa named by Frederic Ward Putnam