''Hemiodontichthys acipenserinus'' is the only

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Hemiodontichthys'', a genus of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Loricariidae The Loricariidae is the largest family of catfish (order Siluriformes), with 92 genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are not ...

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) 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 three largest species alive ...

( order Siluriformes).

Taxonomy

This taxon is often compared with the morphologically similar '' Reganella depressa''; ''Hemiodontichthys'' has been considered the sister genus of ''Reganella'' on the basis of

osteological Osteology () is the scientific study of bones, practised by osteologists. A subdiscipline of anatomy, anthropology, and paleontology, osteology is the detailed study of the structure of bones, skeletal elements, teeth, microbone morphology, func ...

data. However, the similar external morphology of these two taxa could be interpreted as an evolutionary convergence, as they occupy the same ecological niche. In both, there is a rostrum and the loss of maxillary teeth; these could have evolved independently in different lineages subjected to similar environmental constraints. Considering some of the morphological characteristics of the two species, ''Hemiodontichthys'' is now believed to be part of the '' Loricariichthys'' group, while ''Reganella'' is part of the ''

Pseudohemiodon ''Pseudohemiodon'' is a genus of armored catfishes native to South America. Species There are currently seven recognized species in this genus: * '' Pseudohemiodon amazonus'' ( Delsman, 1941) * '' Pseudohemiodon apithanos'' Isbrücker & Nijss ...

'' group.

Distribution

''Hemiodontichthys acipenserinus'' is native to the countries of Bolivia,

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas department/region and single territorial collectivity of France on the northern Atlantic coast of South America in the Guianas. ...

, Guyana and

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

where it occurs in the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

, Essequibo,

Oyapock The Oyapock or Oiapoque (; ; ) is a long river in South America that forms most of the border between the French overseas department of French Guiana and the Brazilian state of Amapá. Course The Oyapock runs through the Guianan moist fores ...

, and

Paraguay River The Paraguay River (Río Paraguay in Spanish, Rio Paraguai in Portuguese, Ysyry Paraguái in Guarani) is a major river in south-central South America, running through Brazil, Bolivia, Paraguay and Argentina. It flows about from its headwaters i ...

basins.

Description

''Hemiodontichthys acipenserinus'' reaches a length of SL. It has been reported that populations from the Amazonian region tend to be more slender than those from the Paraguay and

Guaporé River Guaporé River ( pt, Rio Guaporé, es, Río Iténez) is a river in western Brazil and northeastern Bolivia. It is long; of the river forms the border between Brazil and Bolivia. The Guaporé River is part of the Madeira River basin, which eve ...

Ecology

''Hemiodontichthys acipenserinus'' is a sand dweller that lives partially buried in the substrate, its cryptic coloration providing efficient protection. It lives on the sandy bottom where it feeds on worms and micro-crustaceans. As with other representatives of the ''Loricariichthys'' group, mature males develop hypertrophied lips for brooding eggs. Mature males develop a huge labial veil and teeth with spoon-shaped crowns; females and juveniles, the crowns are pointed. Unlike most loricariids, they don't have well-developed

odontode Odontodes, or dermal teeth, are hard structures found on the external surfaces of animals or near internal openings. They consist of a soft pulp surrounded by dentine and covered by a mineralized substance such as enamel, a structure similar to th ...

s on the snout and

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

s. Eggs are laid in a mass and held by the male in the fold made by its lips. The males bear the cluster of eggs fixed to their lips, which they provide with ventilation during movement. About one week after hatching, the

alevin Fish go through various life stages between fertilization and adulthood. The life of a fish start as spawned eggs which hatch into immotile larvae. These larval hatchlings are not yet capable of feeding themselves and carry a yolk sac whic ...

s leave their parent's protection.

References

{{Taxonbar, from=Q3765521 Loricariini Fish of South America Fish of Bolivia Fish of Brazil Fish of Peru Fish of the Amazon basin Fish of French Guiana Vertebrates of Guyana Taxa named by Pieter Bleeker Taxa named by Rudolf Kner Monotypic ray-finned fish genera Catfish genera