''Squalius alburnoides'', the calandino, 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), ...

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 ...

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 fishes. This species is found in

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

and

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

Taxonomy

''Squalius alburnoides'' was first formally described in 1866 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 a stream near Mérida in Spain. The Adana chub belongs to the genus '' Squalius'', commonly referred to as chubs, which belongs to 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 of the family Leuciscidae. This species is a highly peculiar fish in regard to its

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

and reproduction. It has been derived from hybridisation between females of '' Squalius pyrenaicus'' and males of another, unknown, extinct cyprinid species, and maintains the

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

s of both parental species. ''Squalius alburnoides'' may have various numbers of these genomes ( polyploidy), and may use different reproductive modes to pass them on to the offspring, including

asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the f ...

, normal meiosis and hybridogenesis. It has the first confirmed instance of natural

androgenesis Androgenesis is a system of asexual reproduction that requires the presence of eggs and occurs when a zygote is produced with only paternal nuclear genes. During standard sexual reproduction, one female parent and one male parent each produce h ...

in a vertebrate, where an individual inherits only genes from the father.

Etymology

''Squalius alburnoides'' belongs to the genus ''Squalius'', this name was proposed by the French biologist Charles Lucien Bonaparte in 1837 for a subgenus of the genus ''

Leuciscus ''Leuciscus'' is a genus of freshwater and brackish water ray-finned fishes belonging to the family Leuciscidae, which includes the daces, Eurasian minnows and related species. They are inland water fishes commonly called Eurasian daces. Th ...

'' for the Italian chub ('' Squalius cephalus''), inserting and additional "i" to prevent homonymy with the spurdog genus ''

Squalus ''Squalus'' is a genus of dogfish sharks in the family (biology), family Squalidae. Commonly known as spurdogs, these sharks are characterized by smooth dorsal fin spines, teeth in upper and lower fish jaw, jaws similar in size, caudal peduncle ...

''. In

classical Latin Classical Latin is the form of Literary Latin recognized as a Literary language, literary standard language, standard by writers of the late Roman Republic and early Roman Empire. It formed parallel to Vulgar Latin around 75 BC out of Old Latin ...

the chub and the spurdog were homonyms as ''squalus''. An alternative explanation was that the name is a latinisation of ''squaglio'', a vernacular name for the Italian chub in Rome and its environs. The specific name, ''alburnoides'', means "of the form of '' Alburnus''", an allusion to the long body, notched teeth and upward pointing snout which resembles the shape of the bleaks in the genus ''Alburnus''.

Distribution and habitat

''Squalius alburnoides'' has a wide distribution in the river systems draining into the Atlantic Ocean in the western Iberian Peninsula from the

Douro The Douro (, , , ; ; ) is the largest river of the Iberian Peninsula by discharge. It rises near Duruelo de la Sierra in the Spanish Soria Province, province of Soria, meanders briefly south, then flows generally west through the northern par ...

south to the Guadalquivir, it has been introduced into the Guadalhorce and Júcar rivers in Spain, drainages that flow into the Mediterranean Sea. The calandino is found in rivers and streams at varying altitudes and with differing flows but tends to avoid the wide, deep lowland stretches of rivers.

References

{{Taxonbar, from1=Q21030115, from2=Q840418 Endemic fish of the Iberian Peninsula Fish hybrids Fish described in 1866 alburnoides Taxonomy articles created by Polbot Habitats Directive species