Duopalatinus is a small genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of catfish

Catfish

Catfishes 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 heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

es (order

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Siluriformes) of the family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Pimelodidae

Pimelodidae

Pimelodidae, commonly known as the long-whiskered catfishes, is a family of catfishes .-Taxonomy:Pimelodidae has undergone much revision. Currently, the family contains about 30 genera and about 90 recognized and known but unnamed species...

. It contains two species, D. emarginatus and D. peruanas.

Duopalatinus is classified under the "Calophysus-Pimelodus

Pimelodus

Pimelodus is a genus of catfishes of the family Pimelodidae.Pimelodus is a non-monophyletic assemblage with about 24 species; it is defined by a set of non-derived characters. Species level taxonomy of Pimelodus is still poorly known as well as the phylogenetic relationships within and of the genus...

clade". Within this clade, it is considered a part of the "Pimelodus-group" of Pimelodids, which also includes Pimelodus, Exallodontus,Cheirocerus

Cheirocerus

Cheirocerus is a genus of catfishes of the family Pimelodidae. It includes three species, C. abuelo, C. eques, and C. goeldii.-Distribution and habitat:...

, Iheringichthys

Iheringichthys

Iheringichthys is a small genus of catfish of the family Pimelodidae. It includes two species, I. labrosus and I. megalops.-Appearance and anatomy:...

, Bergiaria

Bergiaria

Bergiaria is a small genus of catfishes of the family Pimelodidae. It contains two species, B. platana and B. westermanni....

, Bagropsis, Parapimelodus

Parapimelodus

Parapimelodus is a small genus of catfishes of the family Pimelodidae. It contains two species, P. nigribarbis and P. valenciennis.-Distribution:...

, Platysilurus

Platysilurus

Platysilurus is a genus of catfishes of the family Pimelodidae. This genus contains three species, P. malarmo, P. mucosus, and P. olallae....

, Platystomatichthys, and Propimelodus

Propimelodus

Propimelodus is a genus of South American catfish of the family Pimelodidae.-Taxonomy:The type species of this genus, P. eigenmanni, was first described in 1946 under the genus Pimelodus. In 2002, the genus Propimelodus was described for this species. Shortly after, in 2006, the species P. caesius...

.

Duopalatinus species are distributed in South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. D. emarginatus inhabits the São Francisco River

São Francisco River

The São Francisco is a river in Brazil. With a length of , it is the longest river that runs entirely in Brazilian territory, and the fourth longest in South America and overall in Brazil...

 basin. D. peruanus is found in the Amazon

Amazon River

The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...

 and Orinoco River basins.

Duopalatinus species grow to about 14–15 centimetres (5.5–5.9 in) SL

Fish measurement

Fish measurement refers to the measuring of the length of individual fish and of various parts of their anatomy. These data are used in many areas of ichthyology, including taxonomy and fisheries biology.-Overall length:...

.