Propimelodus is a 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 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...

n 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...

 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...

.

Taxonomy

The type species

Type species

In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...

 of this genus, P. eigenmanni, was first described in 1946 under the genus 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...

. In 2002, the genus Propimelodus was described for this species. Shortly after, in 2006, the species P. caesius was described to this genus and in 2007 another new species, P. araguayae was described. Other species will be described in the future.

Propimelodus is classified under the "Calophysus-Pimelodus clade". Within this clade, it is considered a part of the "Pimelodus-group" of Pimelodids, which also includes Pimelodus, Exallodontus, Duopalatinus

Duopalatinus

Duopalatinus is a small genus of catfishes of the family Pimelodidae. It contains two species, D. emarginatus and D. peruanas.Duopalatinus is classified under the "Calophysus-Pimelodus clade"...

, 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....

, and Platystomatichthys.

Distribution

P. eigenmanni originate from the lower Amazon River

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...

 as well as large tributaries such as the Xingu

Xingu River

The Xingu River , also called Rio Xingu, is a 1,230-mile long, river in north Brazil; it is a southeast tributary of the Amazon River.-Description and history:...

, Trombetas

Trombetas

The Trombetas is a river on the northern side of the Amazon River. Its confluence with the Amazon is just north of the town of Óbidos, Pará in Brazil. It has its sources in the Guyana highlands, but its long course is frequently interrupted by violent currents, rocky barriers, and rapids...

, Jari River

Jari River

The Jari River, is a northern tributary of the Amazon river on the border between the states of Pará and Amapá in northeastern Brazil. It is in the most downstream regions of the Amazon Basin and borders the Guiana Highlands and the Guianas and French Guiana to the northwest.-Tributaries:*...

, and lower Madeira River

Madeira River

The Madeira River is a major waterway in South America, approximately 3,250 km miles long The Madeira is the biggest tributary of the Amazon...

 in Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

, and the Kourou

Kourou River

The Kourou is a 112 km long river in French Guiana. The town of Kourou is located at its estuary, which is generally used as a pleasure port.Like the river Amazon, it has brown, muddy waters due to sediments picked up from the forest...

 and Oyapock River

Oyapock River

The Oyapock or Oiapoque River is a 370-km long river in South America that forms most of the border between French Guiana and the Brazilian state of Amapá...

s in French Guiana

French Guiana

French Guiana is an overseas region of France, consisting of a single overseas department located on the northern Atlantic coast of South America. It has borders with two nations, Brazil to the east and south, and Suriname to the west...

. P. caesius has the largest range of the genus. P. caesius is also found in many of these regions, with tributary range including Tocantins

Tocantins River

The Tocantins is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" . It runs from south to north for about 2,640 km. It is not really a branch of the Amazon River, although usually so considered, since its waters flow into the...

, Pará

Pará River

The Pará River is the southern arm of the mouth of the Amazon River. It flows round the west and south of the island of Marajó. It takes some water from the main Amazon, however much of its power comes from the Tocantins River flowing from the south. The state capital of Pará, Belém, is located on...

, Jari, Xingu, Trombetas, Madeira, Negro, Purus

Purus

The Purus is a tributary of the Amazon River in South America. Its drainage basin is , and the mean discharge is 8,400 m³/s.It enters the Amazon River west of the Madeira River, which it parallels as far south as the falls of the latter stream...

, Japurá

Japurá River

The Japurá River or Caquetá River is a river about long rising as the Caquetá River in the Andes in the Southwest of Colombia. It flows southeast into Brazil, where it is called the Japurá. The Japurá enters the Amazon River through a network of channels...

, Juruá, and Içá river

Putumayo River

The Içá or Putumayo River is one of the tributaries of the Amazon River, west of and parallel to the Yapura. It forms part of Colombia's border with Ecuador, as well as most of the frontier with Peru...

s. P. araguayae is only known from the middle Araguaia River

Araguaia River

The Araguaia River or, in Portuguese, Rio Araguaia is one of the major rivers of Brazil, and the principal tributary of the Tocantins. It has a total length of approximately 2,627 km. Araguaia means "river of macaws" in the Tupi language....

.

Appearance and anatomy

These fish have three pairs of barbels

Barbel (anatomy)

A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...

. Like other pimelodids, these whiskers are extremely long; the maxillary barbels extend past the base of the caudal fin. Propimelodus species have a rather long adipose fin. Unlike its congeners, P. araguayae has a black spot on its on its dorsal fin.

P. eigenmanni grows not much longer than 20 centimetres (8 in). P. eigenmanni is a pale blue-gray to tan. P. caesius also has an attractive blue coloration.

Ecology

Propimelodus lives in swiftly flowing waters of open channels of the Amazon River

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 many of its large tributaries; P. caesius is one of the most common fish in these habitats.

P. eigenmanni associate with mud or detritus substrates. P. caesius is found in turbid, blackwater habitats over sand, clay, and detritus substrates. P. eigenmanni is nocturnal, found in tidally

Tide

Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....

 influenced freshwater

Fresh Water

Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...

habitats on mud substrate and near dense vegetation. P. araguayae has been found near the edge of rivers among macrophytes.