''Gymnocephalus'' 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 ...

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

from 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 includes 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, pike-perches and

darters 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 ...

. They are from the

Western Palearctic The Western Palaearctic or Western Palearctic is part of the Palaearctic realm, one of the eight biogeographic realms dividing the Earth's surface. Because of its size, the Palaearctic is often divided for convenience into two, with Europe, North ...

area, although one species, ''

Gymnocephalus cernua The ruffe (''Gymnocephalus cernua''), also known as the Eurasian ruffe or pope, is a freshwater fish found in temperate regions of Europe and northern Asia. It has been introduced into the Great Lakes of North America as an invasive species ...

'' has been accidentally introduced to the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...

region where it is regarded as an

invasive species An invasive species is an introduced species that harms its new environment. Invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native spec ...

. They have the common name "ruffe" and resemble the true

es in the genus ''Perca'', but are usually smaller and have a different pattern.

Characteristics

The species within the genus ''Gymnocephalus'' have a number of characters in common including that their

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

s are not completely separate, they have enlarged canals extending from the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

on their heads, the preorbital bone covers the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

ry bone, presence of setiform or bristle-like teeth, having very few or no vomerine and palatine teeth and the possession of three paired bones in the neck, known as extrascapulars, in their lateral line system, of which, two are simple tubes.

Species

There are currently five recognized species in this genus: * '' Gymnocephalus acerina'' ( J. F. Gmelin, 1789) (Donets ruffe) * ''

Gymnocephalus ambriaelacus ''Gymnocephalus ambriaelacus'', the Ammer ruffe, is a species of freshwater ray-finned fish, a ruffe, from the family Percidae which is endemic to Lake Ammer, in the upper Danube basin in southern Germany. This species can reach a maximum length ...

'' Geiger & Schliewen, 2010 * '' Gymnocephalus baloni'' Holčík & K. Hensel, 1974 (Balon's ruffe) * ''

'' (

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

1758 Events January–March * January 1 – Swedish biologist Carl Linnaeus (Carl von Linné) publishes in Stockholm the first volume (''Animalia'') of the 10th edition of ''Systema Naturae'', the starting point of modern zoologic ...

) (ruffe) * '' Gymnocephalus schraetser'' (

) (schraetzer)

Taxonomy

''Gymnocephalus'' was created by the

German German(s) may refer to: * Germany, the country of the Germans and German things **Germania (Roman era) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizenship in Germany, see also Ge ...

physician A physician, medical practitioner (British English), medical doctor, or simply doctor is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through the Medical education, study, Med ...

and

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

Marcus Elieser Bloch (1723–1799) with ''Perca schraester'' as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

. It has traditionally been placed in 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 ...

Percinae 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 ...

alongside the true

of the genus ''Perca''. However, ''Gymnocephalus'' appears to be the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to both the Percinae and to the

Luciopercinae The Luciopercinae is a subfamily of ray-finned fish, classified within the Family (biology), family Percidae, the subfamily includes the pike-perches and zingels. The pike-perches of the genus ''Zander, Sander'' have an Holarctic distribution whi ...

. The 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' treats ''Gymnocephalus'' as the only genus in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

subfamily Acerinae, although Gill's Gymnocephalinae is referred to in some sources. ''

Eschmeyer's Catalog of Fishes Catalog of Fishes is a comprehensive on-line database and reference work on the scientific names of fish species and genera. It is global in its scope and is hosted by the California Academy of Sciences. It has been compiled and is continuously up ...

'' returns to the old classification of keeping ''Gymnocephalus'' in Percinae. The name of the genus is a compound of the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''gymno'' meaning "naked" and ''kephalos'' meaning "head". Within the genus molecular studies have shown that the ruffe ''G. cernua'' is sister to a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

consisting of the Danube ruff ''G. baloni'' and the schraetzer or striped ruffe ''G. schraetser'', and that these last two species originated from a common ancestor about 8 million years ago and it has also been suggested that the relatively newly described ''G. ambriaelacus'' may be

synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with ''G. baloni''. ''G. acerina'' has not had its genetics sampled which would assist understanding of the genus's

phylogenetics In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

Geographic distribution

The species in the genus ''Gymnocephalus'' are found in Europe. One species, ''G. cernua,'' originating from the river

Elbe The Elbe ( ; ; or ''Elv''; Upper Sorbian, Upper and , ) is one of the major rivers of Central Europe. It rises in the Giant Mountains of the northern Czech Republic before traversing much of Bohemia (western half of the Czech Republic), then Ge ...

in Germany, was accidentally introduced to North America in ballast water near the mouth of the St Louis River in

Lake Superior Lake Superior is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. Lake Michigan–Huron has a larger combined surface area than Superior, but is normally considered tw ...

. This species has also been introduced outside of its native range in Europe.

References

External links

* {{Taxonbar, from=Q927216 Percidae Taxonomy articles created by Polbot Taxa named by Marcus Elieser Bloch