''Steindachneridion'' 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 ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

n pimelodid

catfish Catfish (or catfishes; order (biology), order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Catfish are common name, named for their prominent barbel (anatomy), barbels, which resemble a cat's whiskers, though not ...

(

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Siluriformes).

Taxonomy

The first species of the genus, ''S. parahybae'', was described in 1877 by

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 ...

under the name ''Platystoma parahybae''. Later,

Carl H. Eigenmann Carl Henry Eigenmann (March 9, 1863 – April 24, 1927) was a German-American ichthyology, ichthyologist of the late nineteenth and early twentieth centuries, who, along with his wife Rosa Smith Eigenmann, and his zoology students is credited wit ...

and Rosa Smith Eigenmann described ''Steindachneridia'', named for Steindachner, for this species and for ''S. amblyurum'' (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 ...

) in 1888. The next year, Eigenmann and Eigenmann described ''S. doceanum''. In 1918, Miranda Ribeiro described ''S. scriptum'' and ''S. scriptum punctatum''; later, ''S. punctatum'' was studied and considered to be a species of its own. However, because ''Steindachneria'' was already being used, these fish were transferred to ''Steindachneridion'' in 1919. The most recent species, ''S. melanodermatum'', was described by Garavello in 2005. This genus currently includes six

extant Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to: * Extant hereditary titles * Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English * Exta ...

species. Two

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

species of ''Steindachneridion'' have been found. The first to be described, '' S. iherengi'' (Woodward, 1898) was first described to ''

Arius Arius (; ; 250 or 256 – 336) was a Cyrenaica, Cyrenaic presbyter and asceticism, ascetic. He has been regarded as the founder of Arianism, which holds that Jesus Christ was not Eternity, coeternal with God the Father, but was rather created b ...

'', but subsequently moved to ''Steindachneridion''; though originally considered to be of

Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...

age, it was later found to be actually of

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

age. It is known from the Tremembé Formation of Brazil. The second fossil species to be described was '' S. silvasantosi'' Figueiredo & Costa-Carvalho, 1999. The phylogenetic placement of ''Steindachneridion'' and its relationship to other pimelodid genera is unresolved. These fish have been classified with '' Sorubim''-like fish such as '' Brachyplatystoma'' and '' Pseudoplatystoma''. They have also been classified as being more closely related to '' Phractocephalus'' and '' Leiarius''.

Species

The currently recognized species in this genus are: * '' Steindachneridion amblyurum'' ( Eigenmann & Eigenmann, 1888) * '' Steindachneridion doceanum'' ( Eigenmann & Eigenmann, 1889) * '' Steindachneridion melanodermatum'' ( Garavello, 2005) * '' Steindachneridion parahybae'' ( Steindachner, 1877) * '' Steindachneridion punctatum'' ( Miranda-Ribeiro, 1918) * '' Steindachneridion scriptum'' ( Miranda-Ribeiro, 1918)

Distribution and habitat

''Steindachneridion'' species originate from

and are restricted to eastern

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

ian coastal drainages, plus the upper Paraná and

Uruguay River The Uruguay River ( ; ) is a major river in South America. It flows from north to south and forms parts of the boundaries of Brazil, Argentina and Uruguay, separating some of the Argentine provinces of La Mesopotamia from the other two countr ...

basins. ''S. amblyurus'' originates from the Jequitinhonha River basin. ''S. doceanum'' originates from the

Doce River The Doce River ( , "Sweet River") is a river in southeast Brazil with a length of . The river basin is economically important. In 2015, the collapse of a dam released highly contaminated water from mining into the river, causing an ecological d ...

basin. ''S. melanodermatum'' originates from Iguaçu River in

. ''S. parahybae'' originates from

Paraíba do Sul The Paraíba do Sul (), or simply Paraíba, is a river in southeast Brazil. It flows west to northeast from its farthest source at the source of the river Paraitinga to the sea near Campos dos Goytacazes. The river receives its name when it m ...

and Jequitinhonha River basins. ''S. punctatum'' originates from the upper Paraná River and the Uruguay River basins. ''S. scriptum'' originates from the Uruguay River. The large species of ''Steindachneridion'' always occur in swift-flowing, clear-water rivers running over large stony beds. These fish are naturally scarce in their habitats.

Appearance and anatomy

''Steindachneridion'' species are large fish, reaching 100 cm (40 in) in

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

or more. ''S. doceanum'' reaches 42 cm (17 in) in

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 ...

. ''S. melanodermatum'' reaches a length of about 53.2 cm (21 in) SL. ''S. punctatum'' reaches about 70 cm (28 in) SL. These fish have relatively small eyes and heads. They have long maxillary barbels that extend to the base of 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 or

adipose 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 only b ...

s. The adipose fin is relatively long and straight, and its base is longer than the base of 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 ...

Pectoral Pectoral may refer to: * The chest region and anything relating to it. * Pectoral cross, a cross worn on the chest * a decorative, usually jeweled version of a gorget * Pectoral (Ancient Egypt), a type of jewelry worn in ancient Egypt * Pectora ...

and dorsal fin spines are short. Most of these species have light grayish or brownish ground color patterns combined with dark brown, vermiculated dark stripes or spots; however, ''S. doceanum'' has reticulations over its body instead of spots, and ''S. melanodermatum'' is unique in the genus for its dark brown ground color. ''S. amblyurum'' differs from other members of this species by having a rounded

caudal 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 only ...

instead of notched.

Relationship to humans

''Steindachneridion'' species suffer intense anthropogenic pressure, through modification to their habitat and due to

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 stocks, fish stock), resu ...

; consequently, some of them are highly endangered and practically extinct in various parts of their original areas of distribution. Of the six recognized species, all but ''S. punctatum'' are considered

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

by Brazil's Ministry of the Environment.

ICMBio The Chico Mendes Institute for Biodiversity Conservation ( Portuguese: ''Instituto Chico Mendes de Conservação da Biodiversidade'', ICMBio) is a government agency under the administration of the Brazilian Ministry of the Environment. It is nam ...

(Ministry of the Environment, Brazil)
Portaria MMA nº 445, de 17 de dezembro de 2014
. Lista de Especies Ameaçadas - Saiba Mais. Retrieved 1 December 2018. Due to their economic importance as a food source, some

aquaculture Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...

stations are currently developing programs for captive propagation of ''Steindachneridion'' species. Fish produced by these programs would be used in fish farms and to restore natural stocks in degraded habitats.

References

{{Taxonbar, from=Q6513273 Pimelodidae Fish of South America Catfish genera Taxa named by Carl H. Eigenmann Taxa named by Rosa Smith Eigenmann Freshwater fish genera