Steindachneridion

Taxobox
name = "Steindachneridion"
fossil_range = Oligocene - Recentcite journal|url=http://www.ufrgs.br/ni/vol3num4%5CNI_v3n4p607-623lowr.pdf|title=Revision of genus "Steindachneridion" (Siluriformes: Pimelodidae)|journal=Neotropical Ichthyology|first=Julio Cesar|last=Garavello|volume=3|issue=4|pages=607–623|year=2005|format=PDF|doi=10.1590/S1679-62252005000400018]
regnum = Animalia
phylum = Chordata
classis = Actinopterygii
ordo = Siluriformes
familia = Pimelodidae
genus = "Steindachneridion"
genus_authority = Eigenmann & Eigenmann, 1919
subdivision_ranks = Species
subdivision =
* "S. amblyurum"
(Eigenmann & Eigenmann, 1888)
* "S. doceanum"
(Eigenmann & Eigenmann, 1889)
* "S. iherengi" †
(Woodward, 1898)
* "S. melanodermatum"
Garavello, 2005
* "S. scriptum"
(Miranda Ribeiro, 1918)
* "S. silvasantosi" †
Figueiredo & Costa-Carvalho, 1999
* "S. parahybae"
(Steindachner, 1877)
* "S. punctatum"
(Miranda Ribeiro, 1918)
synonyms = "Steindachneria"
Eigenmann & Eigenmann, 1888

"Steindachneridion" is a genus of South American Pimelodid catfish (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 described "Steindachneridia", named for Steindachner, for this species and for "S. amblyurum" (designated as the type species) 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.

There are two fossil species of "Steindachneridion". The first fossil species to be described, "S. iherengi", was first described to "Arius", but subsequently moved to "Steindachneridion"; though originally considered to be of Pleistocene age, it has later been argued that it is actually of Oligocene age. The second fossil species to be described was "S. silvasantosi" in 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".

Distribution and habitat

"Steindachneridion" species originate from South America and are restricted to eastern Brazilian coastal drainages, plus the upper Paraná and Uruguay River basin. "S. amblyurus" originates from the Jequitinhonha River basin.FishBase species|genus=Steindachneridion|species=amblyurus|year=2007|month=May] "S. doceanum" originates from the Doce River basin.FishBase species|genus=Steindachneridion|species=doceanum|year=2007|month=May] "S. melanodermatum" originates from Iguaçu River in Brazil.FishBase species|genus=Steindachneridion|species=melanodermatum|year=2007|month=May] "S. parahybae" originates from Paraíba do Sul and Jequitinhonha River basins.FishBase species|genus=Steindachneridion|species=parahybae|year=2007|month=May] "S. punctatum" originates from the upper Paraná River and the Uruguay River basins.FishBase species|genus=Steindachneridion|species=punctatum|year=2007|month=May] "S. scriptum" originates from the Uruguay River.FishBase species|genus=Steindachneridion|species=scripta|year=2007|month=May]

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 sized fishes, reaching 100 centimetres (40 in) TL or more. "S. doceanum" reaches 42 cm (17 in) SL. "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 head. They have long maxillary barbels that extend to the base of the dorsal fin or the adipose fin. The adipose fin is relatively long and straight, and its base is longer than the base of the anal fin. Pectoral and dorsal fin spines are short. Most of these species have light grayish or brownish ground color pattern 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 instead of a caudal fin that is 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. 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 as well to restore natural stocks in degraded habitats.cite journal|title=First chromosome data on "Steindachneridion scripta" (Pisces, Siluriformes, Pimelodidae) from Brazilian rivers: Giemsa, CBG, G-, and RE banding|url=http://www.funpecrp.com.br/gmr/year2005/vol4-4/pdf/gmr0144.pdf|first=Ana Claudia|last=Swarça|coauthors=Fenochhio, Alberto Sergio; Cestari, Marta Margarete; Dias, Ana Lúcia|journal=Genet. Mol. Res.|volume=4|issue=4|pages=734–741|year=2005|format=PDF]

References