''Steindachneridion'' is a

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 nom ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

n pimelodid

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive ...

( order Siluriformes).

Taxonomy

The first species of the genus, ''S. parahybae'', was described in 1877 by Franz Steindachner under the name ''Platystoma parahybae''. Later, Carl H. Eigenmann and

Rosa Smith Eigenmann Rosa Smith Eigenmann (October 7, 1858 – January 12, 1947) was an American ichthyologist (the branch of zoology devoted to the study of fish), as well as a writer, editor, former curator at the California Academy of Sciences, and the first libra ...

described ''Steindachneridia'', named for Steindachner, for this species and for ''S. amblyurum'' (designated as the

type species In 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 species that contains the biological type specime ...

) 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 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 preserved ...

species of ''Steindachneridion'' have been found. The first to be described, '' S. iherengi'' (Woodward, 1898) was first described to '' Arius'', but subsequently moved to ''Steindachneridion''; though originally considered to be of

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

age, it was later found to be actually of Oligocene age. 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 ''Pseudoplatystoma'' is a genus of several South American catfish species of family (biology), family Pimelodidae. The species are known by a number of different common names. They typically inhabit major rivers where they prefer the main channel ...

''. They have also been classified as being more closely related to '' Phractocephalus'' and ''

Leiarius ''Leiarius'' is a genus of long-whiskered catfishes native to South America. Most of the genus' species are found in the aquarium hobby as ornamental fish. Species There are currently four recognized species in this genus: * '' Leiarius arekaim ...

''.

Species

The currently recognized species in this genus are: * '' Steindachneridion amblyurum'' (

Eigenmann Eigenmann is a surname. Notable persons with that surname include: * Andi Eigenmann (born 1990), Filipino actress * Carl H. Eigenmann (1863–1927), German–American ichthyologist, husband of Rosa Eigenmann * Eduardo de Mesa Eigenmann, birth name ...

, 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 ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

ian coastal drainages, plus the upper Paraná and

Uruguay River The Uruguay River ( es, Río Uruguay, ; pt, Rio Uruguai, ) 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 M ...

basins. ''S. amblyurus'' originates from the

Jequitinhonha River The Jequitinhonha River () flows mainly through the Brazilian state of Minas Gerais. Its source lies near Diamantina in the Espinhaço Mountains at an elevation of , after which it flows northward and then east-northeastward across the uplands. ...

basin. ''S. doceanum'' originates from the Doce River basin. ''S. melanodermatum'' originates from Iguaçu River in

. ''S. parahybae'' originates from Paraíba do Sul 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. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

or more. ''S. doceanum'' reaches 42 cm (17 in) in standard length. ''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 located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

s or

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 se ...

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

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 * Pectorali ...

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 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 ...

instead of notched.

Relationship to humans

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

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 the Brazilian Ministry of the Environment's administrative arm."Brazilian Federal Law 11.516/2007 (Por ...

(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 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