Harttia 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...

.

Taxonomy

As of 1997, Harttia was considered a monophyletic

Monophyly

In common cladistic usage, a monophyletic group is a taxon which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group. The term is synonymous with the uncommon term holophyly...

 taxon. However, Harttia is in need of revision. For example, the synonymy

Synonym (taxonomy)

In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...

 of Cteniloricaria

Cteniloricaria

Cteniloricaria is a genus of catfishes of the family Loricariidae. It includes three species, C. fowleri, C. maculata, and C...

with Harttia is questionable because it rests solely on the characteristics of Harttia fowleri without considering the type species

Biological type

In biology, a type is one particular specimen of an organism to which the scientific name of that organism is formally attached...

 of Cteniloricaria.

Distribution and habitat

Distribution of Harttia species primarily includes rivers draining the Guyana Shield, coastal rivers in northeastern 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 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...

 basin. The greatest species diversity of Harttia, occurs in the Pre-Cambrian

Cambrian

The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...

 Brazilian Shield region. Only H. platystoma and H. merevari are known from Venezuela

Venezuela

Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...

. These rheophilic

Rheophile

A rheophile is an organism that prefers to live in fast moving water.-Insects:*Many aquatic insects living in riffles require current to survive.*Epeorus sylvicola, a rheophilic mayfly species .-Fish:...

 fishes are found in the upper courses of rivers over rocky and sandy bottoms. Harttia species are thought to be able to exploit areas with the strongest current, because of its extremely depressed body and long caudal peduncle, comparing to other species.

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 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 on the pectoral fin spines and along the margins of the snout in mature males.

Harttia exhibits considerable karyotypic

Karyotype

A karyotype is the number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species, or an individual organism.p28...

 diversity with chromosome numbers between 2n = 52 and 2n = 58 in the four species characterized.