The Iberian nase (''Pseudochondrostoma polylepis'') is a species of

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

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 ...

belonging to 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 ...

Leuciscidae Leuciscidae is a family of freshwater ray-finned fishes, formerly classified as a subfamily of the Cyprinidae, which contains the true minnows. Members of the Old World (OW) clade of minnows within this subfamily are known as European minnow ...

, which includes the daces, Eurasian minnows and related species. This species is endemic to the

Iberian Peninsula The Iberian Peninsula ( ), also known as Iberia, is a peninsula in south-western Europe. Mostly separated from the rest of the European landmass by the Pyrenees, it includes the territories of peninsular Spain and Continental Portugal, comprisin ...

in Spain and Portugal.

Taxonomy

The Iberian nase was first formally described in 1864 as ''Chondrostoma polylepis'' by the Austrian

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

Franz Steindachner Franz Steindachner (11 November 1834 in Vienna – 10 December 1919 in Vienna) was an Austrian zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachner des ...

with its type locality given as

Crato, Portugal Crato () is a municipality in Portalegre District in Portugal. The population in 2011 was 3,708, in an area of 398.07 km2. The present Mayor is José Correia Luz, elected by the Socialist Party. The municipal holiday is Easter Monday. Parish ...

. It was designated 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 ...

of the genus ''

Pseudochondrostoma ''Pseudochondrostoma'' is a genus of freshwater ray-finned fish belonging to the family Leuciscidae, which includes the daces, Eurasian minnows and related species. The fishes in this genus occur in the Iberian Peninsula. They are commonly known ...

'' within 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 ...

Leuciscinae Leuciscinae is a subfamily of freshwater Actinopterygii, ray-finned fishes belonging to the Family (biology), family Leuciscidae, which includes the fishes known as daces, chubs, shiners and minnows. The fishes in this subfamily are mainly found i ...

of the family

. This genus was proposed in 2007 for three species which were split from ''Chondrostoma'' on the basis of genetic evidence.

Etymology

The Iberian nase is the type species of the genus ''Pseudochondrostoma'', a name which prefixes ''Chondrostoma'' with ''pseudo-'' which means "false", applied because although the fishes in this genus are similar in appearance to the nases in the genus ''Chondrostoma'' such similarities are due to

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

rather than common ancestry, and are therefore "false". The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

, ''polylepis'', means "many scales", a reference to number of scales along 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 ...

compared to '' Chondrostoma nasus'', a species which had been confused with this one.

Description

The Iberian nase is told apart from other members of the genus ''Pseudochondrostoma'' by the edge of the lower jaw being straight; the lateral line having between 61 and 75 scales along its length; and the

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

has branched fin rays. This species has a maximum

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 ...

of .

Distribution and habitat

The Iberian nase is endmeic to the Iberian Peninsula where it is found in the central part of the Peninsula in rivers draining into the Atlantic from the

Tagus The Tagus ( ; ; ) is the longest river in the Iberian Peninsula. The river rises in the Montes Universales between Cuenca and Teruel, in mid-eastern Spain, flows , generally westward, and empties into the Atlantic Ocean in Lisbon. Name T ...

south to the

Sado River The Sado () is a river in southern Portugal; it is one of the major rivers in the country. It flows in a northerly direction (the only major Portuguese river to do so) through from its springs in the hills of Ourique before entering the Atlanti ...

in Spain and Portugal. It has also been introduced to the

Segura Segura may refer to: Geography * Segura (river), a tributary of the Mediterranean Sea in southeastern Spain * Sierra de Segura, a mountain range in southeastern Spain * Segura, Gipuzkoa, a town in the Basque Country, northern Spain * Segura de lo ...

and

Júcar The Júcar () or Xúquer () is a river in Spain, on the Iberian Peninsula. The river runs for approximately 509 km. Its source is located at Ojuelos de Valdeminguete, in the municipality of Tragacete, province of Cuenca, on the eastern fla ...

rivers systems in Eastern Spain and the Arade River in the

Algarve The Algarve (, , ) is the southernmost NUTS statistical regions of Portugal, NUTS II region of continental Portugal. It has an area of with 467,495 permanent inhabitants and incorporates 16 municipalities (concelho, ''concelhos'' or ''município ...

, Portugal. This species is found in perennial lowland river channels and larger tributaries. It has colonised some reservoirs where they can reach suitable

spawning Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...

habitat upstream.

Biology

The Iberian nase has a diet dominated by

periphyton Periphyton is a complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus that is attached to submerged surfaces in most aquatic ecosystems. The related term Aufwuchs ( German "surface growth" or "overgrowth", ) refers to the ...

, with some detritus and benthic invertebrates. The periphyton is scraped from the surface of submerged surfaces with its specialised mouthparts. The spawning season runs from April to July, depending on location and environmental conditions such as water temperature. At this time the mature adults migrate upstream to beds of gravel or other coarse substrates in shallow, fast-flowing water. The breeding males develop many small nuptial tubercles on the head and body. The juveniles and a few subadults are reported to remain in upstream habitats all year, preferring riffles and runs with submerged cover. Many rivers and streams in Northwestern Iberia are characterised by very variable seaonal discharges and the upper reaches may have their water levels lowered significantly or they may completely dry in the summer. Some subadult fishes thus endure such periods of drought by taking refuge in deeper relict pools.

Conservation

The Iberian nase is classified as

Near-threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to endangerment in the near future, but it does not currently qu ...

by the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

. The threats to this species include habitat modification, pollution, climate change and

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 ...

. It has also colonised some rivers in eastern Spain by exploiting canals which have linked its native drainages to the Segura and Júcar drainages. The arrival of the Iberian nase in these systems may have contributed to the decline of the Júcar nase (''

Parachondrostoma arrigonis ''Parachondrostoma arrigonis'', the Júcar nase, is a species of freshwater ray-finned fish belonging to the family Leuciscidae, which includes the daces. Eurasian minnows and related fishes. This species is endemic to Spain. Taxonomy ''Parachon ...

'') by hybridisation and competition. This species also hybridises with other Iberian nase species.

References

{{Taxonbar, from=Q263911 Pseudochondrostoma Fish described in 1864 Taxa named by Franz Steindachner Taxonomy articles created by Polbot Freshwater fish of Europe Endemic fish of the Iberian Peninsula Fauna of Spain Fauna of Portugal Habitats Directive species