Metaloricaria 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 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...

 Loricariidae

Loricariidae

Loricariidae is the largest family of catfish , with almost 700 species and new species being described each year. Loricariids originate from fresh water habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are noted for the bony plates covering their bodies and...

. It includes two species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, M. nijsseni and M. paucidens.

Taxonomy

The phylogenetic

Phylogenetics

In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...

 position of Metaloricaria remains uncertain. Though classified in the tribe Harttiini in the subfamily Loricariinae

Loricariinae

Loricariinae is a subfamily of the family Loricariidae of catfish . This subfamily is divided into two tribes and about 30 genera.-Taxonomy:...

, the length of the maxillary 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...

 (longer than in all other Harttiini), low number of teeth and their reduced size, reduction of the number of caudal-fin rays, and sexual dimorphism

Sexual dimorphism

Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

 reminiscent of that seen in the Rineloricaria

Rineloricaria

Rineloricaria is a genus of freshwater tropical catfish belonging to the Loricariidae family. They are commonly called whiptail catfish because of the long filament that grows out of the tip of the caudal fin that is characteristic of the genus...

group, tend to support a closer relationship of Metaloricaria with the tribe Loricariini.

Distribution and habitat

Metaloricaria is only known from the Guiana Shield 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...

 and Surinam where the species occupy an ecological niche similar to that of Harttia

Harttia

Harttia is a genus of catfishes of the family Loricariidae.-Taxonomy:As of 1997, Harttia was considered a monophyletic taxon. However, Harttia is in need of revision...

. The species are rarely found in their natural environment and inhabit primarily streams over rocky and sandy substrates. M. nijsseni occurs in Suriname

Suriname River

The Suriname River is 480 km long and flows through the country Suriname. Its sources are located in the Guiana Highlands on the border between the Wilhelmina Mountains and the Eilerts de Haan Mountains...

, Saramacca

Saramacca River

Saramacca River is a river in Suriname . Arawaks named this river "Surama", and today's name "Saramacca" is probably derived from it. It originates in the Wilhelmina Mountains and flows northwards and enters the Atlantic Ocean together with Coppename River. It has a river basin of 9.400 km² and...

, Nickerie

Nickerie River

The Nickerie is a river in the northwestern part of Suriname.The river rises in the Bakhuys Mountains and then flows to the North where it forms part of the border between the Coronie and Nickerie districts...

, and Corantijn River basins. M. paucidens is not an abundant species, inhabiting zones of rapids with strong illumination in the Oyapock

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...

, Sinnamary

Sinnamary River

The Sinnamary River is a river in French Guiana. It rises in the center of the country, flowing north until it reaches the Atlantic Ocean near the town of Sinnamary. A hydropower dam was built near Petit-Saut between 1989 and 1994....

, and Marowijne River basins.

Description

Sexual dimorphism

Sexual dimorphism

Sexual dimorphism is a phenotypic difference between males and females of the same species. Examples of such differences include differences in morphology, ornamentation, and behavior.-Examples:-Ornamentation / coloration:...

 includes hypertrophied development of odontode

Odontode

Odontodes, or dermal teeth, are hard structures found on the external surfaces of animals or near internal openings. They comprise a soft pulp surrounded by dentine and covered by a mineralized substance such as enamel, a structure similar to that of teeth. They generally do not have the same...

s arranged in brushes along the sides of the head and on the spine and rays of the pectoral fins in mature males. Females also possess such brushes along sides of the head, but do not seem to develop pectoral-fin enlarged odontodes. Metaloricaria species grow to about 27–29.5 centimetre

Centimetre

A centimetre is a unit of length in the metric system, equal to one hundredth of a metre, which is the SI base unit of length. Centi is the SI prefix for a factor of . Hence a centimetre can be written as or — meaning or respectively...

s (10.6–11.6 in

Inch

An inch is the name of a unit of length in a number of different systems, including Imperial units, and United States customary units. There are 36 inches in a yard and 12 inches in a foot...

) 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:...

.