''Cobitis narentana'' is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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 ...

in the true loach

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 ...

(Cobitidae). It is found in

Bosnia and Herzegovina Bosnia and Herzegovina, sometimes known as Bosnia-Herzegovina and informally as Bosnia, is a country in Southeast Europe. Situated on the Balkans, Balkan Peninsula, it borders Serbia to the east, Montenegro to the southeast, and Croatia to th ...

and

Croatia Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...

. This fish was long believed to be part of the widespread

spined loach The spined loach (''Cobitis taenia'') is a common freshwater fish in Europe. It is sometimes known as spotted weather loach, not to be confused with the "typical" weather loaches of the genus '' Misgurnus''. This is the type species of the spiny ...

(''C. taenia'').

Cladistic Cladistics ( ; from Ancient Greek 'branch') is an approach to biological classification in which organisms are categorized in groups ("clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is ...

analysis of

DNA sequence A nucleic acid sequence is a succession of bases within the nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. This succession is denoted by a series of a set of five different letters that indicate the order of the nu ...

data (

nDNA Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. It ...

RAG-1 and S7

ribosomal protein A ribosomal protein (r-protein or rProtein) is any of the proteins that, in conjunction with rRNA, make up the ribosomal subunits involved in the cellular process of translation. ''E. coli'', other bacteria and Archaea have a 30S small subunit ...

intron An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. The word ''intron'' is derived from the term ''intragenic region'', i.e., a region inside a gene."The notion of the cistron .e., gen ...

1, and

mtDNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the DNA contained in ...

cytochrome ''b'') confirms that it is properly treated as full species. It belongs to a group including '' C. bilineata'', '' C. dalmatina'' and an undescribed species from the

Bosnia Bosnia and Herzegovina, sometimes known as Bosnia-Herzegovina and informally as Bosnia, is a country in Southeast Europe. Situated on the Balkans, Balkan Peninsula, it borders Serbia to the east, Montenegro to the southeast, and Croatia to th ...

n-Croatian border region. The

Adriatic The Adriatic Sea () is a body of water separating the Italian Peninsula from the Balkans, Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Se ...

endemics separated from the ancestors of ''C. bilineata'', today widespread immediately south of the

Alps The Alps () are some of the highest and most extensive mountain ranges in Europe, stretching approximately across eight Alpine countries (from west to east): Monaco, France, Switzerland, Italy, Liechtenstein, Germany, Austria and Slovenia. ...

, around 6–5.5

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

. This was during the

Messinian salinity crisis In the Messinian salinity crisis (also referred to as the Messinian event, and in its latest stage as the Lago Mare event) the Mediterranean Sea went into a cycle of partial or nearly complete desiccation (drying-up) throughout the latter part of ...

, when drainage basins throughout the

Mediterranean The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...

region changed their course. ''C. dalmatina'' appears to be quite similar to ''C. narentana'' as regards the

mitochondrial DNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...

sequence, but the nuclear DNA sequences differ far more. This typically occurs in cases of

hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two diff ...

ization between distinct but related species. In the present case, ''C. narentana'' would have mated with ''C. dalmatina'' males, perhaps during some

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58glacial A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

. Its natural

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

s are

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

s, freshwater

lake A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...

s and freshwater

marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

es of the

Neretva River The Neretva (, sr-Cyrl, Неретва), also known as Narenta, is one of the largest rivers of the eastern part of the Adriatic basin. Four hydroelectric power plants with large dams (higher than 15 metres) provide flood protection, electri ...

basin. It is threatened by

habitat loss 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 ...

. It can grow to

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

and total length.

References

Cobitis Messinian Fish described in 1928 Taxa named by Stanko Karaman Taxonomy articles created by Polbot Freshwater fish of Europe Endemic fish of the Neretva basin Fish of Bosnia and Herzegovina {{Cobitidae-stub