Cottidae
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The Cottidae are a family of fish in the superfamily Cottoidea, the sculpins. Following major taxonomic revisions, it contains about 118 species in 18 genera, the vast majority of which are either restricted to freshwater habitats or are amphidromous.<ref>Template:Cite web</ref> They are referred to simply as cottids to avoid confusion with sculpins of other families.<ref name="kane">Kane, E. A. and T. E. Higham. (2012). Life in the flow lane: differences in pectoral fin morphology suggest transitions in station-holding demand across species of marine sculpin. Template:Webarchive Zoology (Jena) 115(4), 223–32.</ref>
Cottids are distributed throughout the Northern Hemisphere, especially in boreal and colder temperate climates.<ref name=kane/> They are especially diverse in Lake Baikal and surrounding river basins. Only a few cottids inhabit marine habitats. Other sculpins restricted to marine habitats are now placed in the family Psychrolutidae.<ref name="S&B2014">Template:Cite journal</ref> In Lake Baikal, many cottids live in deep water, below Template:Cvt.<ref name="fb">Froese, R. and D. Pauly. (Eds.) Abyssocottidae. FishBase. 2011.</ref> There are 24 known species in seven genera.<ref name="fb" /> These include, for instance, Abyssocottus korotneffi and Cottinella boulengeri which are among the deepest-living freshwater fish.<ref>Jakubowski, M. (1997). Morphometry of gill respiratory area in the Baikalian deep-water sculpins Abyssocottus korotneffi and Cottinella boulengeri (Abyssocottidae, Cottoidei). Journal of Morphology 233(2), 105–12.</ref> Baikal is the deepest lake on Earth (Template:Cvt) and sculpins occupy even its greatest depths.<ref name="hunt">Hunt, D. M., et al. (1997). Molecular evolution of the cottoid fish endemic to Lake Baikal deduced from nuclear DNA evidence. Molecular Phylogenetics and Evolution 8(3), 415–22.</ref>
Most cottids are small fish, under Template:Convert in length.<ref name=EoF>Template:Cite book</ref>
The earliest known skeletal remains of cottids are of Cottus cervicornis (taxonomy uncertain) from the Early Oligocene of Belgium. Cottids become more common in the fossil record from the Miocene onwards.<ref>Template:Cite journal</ref>
Taxonomy
The Cottidae was first recognised as a taxonomic grouping by the French zoologist Charles Lucien Bonaparte in 1831.<ref name = VDLEF/> The composition of the family and its taxonomic relationships have been the subject of some debate among taxonomists. The 5th edition of Fishes of the World retains a rather conservative classification, although it includes the families Comephoridae and Abbyssocottidae as subfamilies of the Cottidae recognising that these taxa are very closely related to some of the freshwater sculpins in the genus Cottus.<ref name="Nelson5">Template:Cite book</ref> More recently, phylogenetic studies have redefined Cottidae to be largely restricted to the freshwater sculpins, i.e. Cottus, Leptocottus, Mesocottus, Trachidermus, and the species flock in and around Lake Baikal, and the marine genera are placed in the Psychrolutidae.<ref name="S&B2014" /> Eschmeyer's Catalog of Fishes follows this classification.<ref name="CofF" />
Based on Eschmeyer's Catalog of Fishes (2025):<ref name="CofF">Template:Cof family</ref>
- Family Cottidae Bonaparte, 1831
- Genus Abyssocottus Berg, 1906
- Genus Alpinocottus Bogdanov, 2023
- Genus Asprocottus Berg, 1906
- Genus Batrachocottus Berg, 1903
- Genus Comephorus Lacépède, 1800
- Genus Cottinella Berg, 1907
- Genus Cottocomephorus Pellegrin, 1900
- Genus Cottus Linnaeus, 1758
- Genus Cyphocottus Sideleva, 2003
- Genus †Kerocottus Kimmel, 1975 (fossil; late Neogene of Oregon, USA)<ref>Template:Cite journal</ref>
- Genus Leocottus Palmer, 1961
- Genus Leptocottus Girard, 1854
- Genus Limnocottus Berg, 1906
- Genus Neocottus Sideleva, 1982
- Genus Procottus Gratzianov, 1902
- Genus Rheopresbe Jordan & Starks, 1904
- Genus Trachidermis Heckel, 1837
Evolution
Molecular studies based on mitochondrial DNA suggest that the Lake Baikal cottids, previously placed in the subfamilies Abyssocottinae, Cottocomephorinae & Comephorinae (Baikal oilfish), together make a monophyletic group that has originated and diversified within the lake relative recently, since the Pliocene. The ancestors of this species flock comprising more than 30 species belonged to the widespread freshwater sculpin genus Cottus (in Cottidae). The Abyssocottidae itself appears as a natural group within this radiation, except that also the genus Batrachocottus should be included.<ref name="Kontula">Template:Cite journal</ref>