''Prietella'' is a small

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of North American freshwater catfishes found in

Mexico Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guate ...

and

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

, and restricted to underground waters.

Taxonomy

''Prietella'' has been confirmed to be

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic ...

and to be the

sister group 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 ...

of the '' Noturus''. The

karyotype A karyotype is the general appearance of the complete set of metaphase chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is disce ...

of ''P. phreatophila'' is indistinguishable from one of the genus ''Noturus''; however, its

diploid number Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respecti ...

of 50

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...

s differs from the proposed ancestral ''Noturus'' karyotype of 54–56 chromosomes. However, this relationship has not been supported by preliminary mitochondrial DNA sequence data. Despite similarity to other cave-dwelling species of Ictaluridae, they are not closely related.

Species

There are currently two recognized species in this genus: * '' Prietella lundbergi'' S. J. Walsh & C. R. Gilbert, 1995 (Phantom blindcat) * '' Prietella phreatophila'' Carranza, 1954 (Mexican blindcat)

Distribution and habitat

The distribution of ''Prietella'' now is known to extend from the very northern part of the state of

Coahuila Coahuila (), formally Coahuila de Zaragoza (), officially the Free and Sovereign State of Coahuila de Zaragoza ( es, Estado Libre y Soberano de Coahuila de Zaragoza), is one of the 32 states of Mexico. Coahuila borders the Mexican states of N ...

, very near the international boundary, to the southernmost

Tamaulipas Tamaulipas (), officially the Free and Sovereign State of Tamaulipas ( es, Estado Libre y Soberano de Tamaulipas), is a state in the northeast region of Mexico; one of the 31 states which, along with Mexico City, comprise the 32 Federal Entiti ...

, 750 kilometres (470 mi) away to the southeast. The distribution of ''P. lundbergi'' is very restricted; ''P. lundbergi'' is known from two springs of the Tamesí River drainage in the Tamaulipas state of Mexico. ''P. phreatophila'' has a greater distribution than ''P. lundbergi''; ''P. phreatophila'' originates from the Bravo River basin, Coahuila, from near Múzquiz northward to about 50 km (31 mi) southwest of

Ciudad Acuña Ciudad Acuña, also known simply as Acuña, (originally Garza Galán, later Villa Acuña) is a city located in the Mexican state of Coahuila, at and a mean height above sea level of . It stands on the Rio Grande (locally known as the Río Bravo ...

and to near

Allende Salvador Guillermo Allende Gossens (, , ; 26 June 1908 – 11 September 1973) was a Chilean physician and socialist politician who served as the 28th president of Chile from 3 November 1970 until his death on 11 September 1973. He was the fi ...

, Mexico. In 2016, ''P. phreatophila'' was confirmed from

, near the Mexican border. Both species occupy different

Gulf of Mexico The Gulf of Mexico ( es, Golfo de México) is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United S ...

drainages and are separated by about 600 km (370 mi). ''P. lundbergi'' is a cave-restricted species. ''P. phreatophila'' occurs in wells. Most ''Phreatophila'' have been found well in habitats that likely have relatively little short-term fluctuation in environmental parameters. For the most part, they are found in still pools; they have never been seen in shallow running water. Often they are associated with a silt substrate.

Description

Like other cave species of catfish including the ictalurids '' Trogloglanis pattersoni'' and ''

Satan eurystomus The widemouth blindcat (''Satan eurystomus'') is a species of North American freshwater catfish endemic to Texas in the United States. It is the only species in the genus ''Satan''. Description It was first discovered inhabiting a well, and is ...

'', ''Prietella'' species lack pigmentation and eyes and have a reduced lateral line. In ''Prietella'', the lateral line is more reduced than in other members of the subfamily; after the gill opening, it is reduced to three or fewer pores. ''P. lundbergi'' differs from ''P. phreatophila'' by a number of characteristics including a reduced or absent

swimbladder The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ that contributes to the ability of many bony fish (but not cartilaginous fish) to control their buoyancy, and thus to stay at their current water depth w ...

, a more emarginate to weakly forked

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

, and a more deeply notched

adipose fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as s ...

. ''P. lundbergi'' grows to about 4.5 centimetres (1.8 in) SL.

Behavior

Jaw-locking behaviors have been observed in ''P. phreatophila''. Fish that have been presumed to be males when first coming in contact with each other will engage in this behavior that is thought to establish a social dominance hierarchy. Jaw-locking usually lasts less than 30 minutes but has been recorded to last for many hours. The dominance relationships are long-term; the same two fish usually do not engage in this behavior again. ''P. phreatophila'' may lie motionless or drift in the current with their breathing slowed. Though they may be awakened by disturbances, this behavior is likely due to lack of predators in their habitat as this behavior would likely leave them extremely vulnerable to predation.

Relationship to humans

Trade of ''P. phreatophila'' is restricted in

Germany Germany, officially the Federal Republic of Germany (FRG),, is a country in Central Europe. It is the most populous member state of the European Union. Germany lies between the Baltic and North Sea to the north and the Alps to the sou ...

. Both species of ''Prietella'' are on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

. ''P. lundergi'' is a

vulnerable species A vulnerable species is a species which has been categorized by the International Union for Conservation of Nature as being threatened with extinction unless the circumstances that are threatening its survival and reproduction improve. Vulne ...

, and ''P. phreatophila'' is an endangered species. ''P. phreatophila'' is threatened by

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidat ...

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

and

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in the ...

. It has been noted that ''P. phreatophila'' should be considered a

threatened species Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...

due to being found in more localities than previously thought and recommended that ''P. lundbergi'' be considered endangered due to its extreme rarity.

References

{{Taxonbar, from=Q5013972 Catfish genera Freshwater fish of North America Freshwater fish genera