''Otocinclus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 ...

in the

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

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 ...

native to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

, commonly known as "dwarf suckers" or "otos". This genus, like other

loricariids 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 ...

, is characterized by rows of armour plating covering the body, as well as the underslung

suckermouth In fish, a suckermouth is a ventrally-oriented (inferior) mouth adapted for grazing on algae and small organisms that grow on submerged objects. All Loricariidae possess a suckermouth as do the cypriniform algae eaters of the genus ''Gyrinocheilus' ...

. They are generally small in size; ''O. tapirape'' is the smallest of the species (2.4 cm), while ''O. flexilis'' is the biggest (5.5 cm). These

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 ...

have adaptations that allow them to breathe air. A duct forms at the junction between the

esophagus The esophagus ( American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to ...

and the

stomach The stomach is a muscular, hollow organ in the gastrointestinal tract of humans and many other animals, including several invertebrates. The stomach has a dilated structure and functions as a vital organ in the digestive system. The stomach i ...

and expands into an enlarged, ring-like diverticulum, characteristic of this genus, which allows air-breathing.Armbruster, J.W. (1998)
Modifications of the Digestive Tract for Holding Air in Loricariid and Scoloplacid Catfishes.
''Copeia, 1998 (3): 663–675.'' ''Otocinclus'' are popular

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

fish, and they are often purchased as

algae eater Algae eater or algivore is a common name for any bottom-dwelling or filter-feeding aquatic animal species that specialize in feeding on algae and phytoplanktons. Algae eaters are important for the fishkeeping hobby and many are commonly kept b ...

s. It is difficult to breed them in captivity, and only wild caught ''Otocinclus'' are available to hobbyists. This genus is widely distributed east of the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

, throughout the lowlands from northern

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

to northern

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

, but are generally absent from 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 technology c ...

and the Orinoco lowlands.

Etymology

The ''Otocinclus'' name is derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''oto'', meaning ear and the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''cinclus'', meaning a latticework, an allusion to the holes in the head in the region of the ear.

Taxonomy

''Otocinclus'' is the most basal genus of the

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English language, English is in the discipline of anthropology. This definition is contested, in p ...

Hypoptopomatini of the subfamily

Hypoptopomatinae The Hypoptopomatinae are a subfamily of catfishes (order Siluriformes) of the family Loricariidae, composed of 17 genus, genera and approximately 80 species. This subfamily represents about one-tenth of all loricariid species. It has been divide ...

. However,

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

relationships are currently under study and this genus may eventually be relocated.Lehmann, A., P. (2006)
''Otocinclus batmani'', a new species of hypoptopomatine catfish (Siluriformes: Loricariidae) from Colombia and Peru.
''Neotropical Ichthyology, 4 (4): 379–383.'' Its

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

is supported by seven

derived Derive may refer to: * Derive (computer algebra system), a commercial system made by Texas Instruments * ''Dérive'' (magazine), an Austrian science magazine on urbanism *Dérive, a psychogeographical concept See also * *Derivation (disambiguatio ...

features. ''O. batmani'', ''O. bororo'', ''O cocama'', ''O. huaorani'', ''O. mariae'' and ''O. mura'' form a monophyletic group within this genus. A monophyletic group is also formed by ''O. flexilis'', ''O. mimulus'' and ''O. xakriaba'', which all share

mimic MIMIC, known in capitalized form only, is a former simulation computer language developed 1964 by H. E. Petersen, F. J. Sansom and L. M. Warshawsky of Systems Engineering Group within the Air Force Materiel Command at the Wright-Patterson AFB in ...

ry as a

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to hav ...

Species

There are currently 19 recognized species in this genus: *''

Otocinclus arnoldi ''Otocinclus arnoldi'' is a species of Loricariidae, armoured catfish native to South America, where it occurs in the lower Paraná River, río Paraná drainage, in the lower and middle Uruguay River, rio Uruguai and in the río de La Plata. This ...

Regan The family name Regan, along with its cognates O'Regan, O Regan, Reagan, and O'Reagan, is an Anglicized form of the Irish surname Ó Riagáin or Ó Ríogáin, from Ua Riagáin. The meaning is likely to have originated in ancient Gaelic ''ri'' ...

, 1909 * '' Otocinclus batmani'' Lehmann A., 2006 * '' Otocinclus bororo''

Schaefer Schaefer is an alternative spelling and cognate for the German word ''schäfer'', meaning 'shepherd', which itself descends from the Old High German '' scāphare''. Variants "Shaefer", "Schäfer" (a standardized spelling in many German-speaking ...

, 1997 * '' Otocinclus caxarari''

, 1997 * ''

Otocinclus cocama ''Otocinclus'' is a genus of catfish in the family Loricariidae native to South America, commonly known as "dwarf suckers" or "otos". This genus, like other loricariids, is characterized by rows of armour plating covering the body, as well as the ...

'' R. E. dos Reis, 2004 * '' Otocinclus flexilis''

Cope The cope (known in Latin as ''pluviale'' 'rain coat' or ''cappa'' 'cape') is a liturgical vestment, more precisely a long mantle or cloak, open in front and fastened at the breast with a band or clasp. It may be of any liturgical colour. A c ...

, 1894 * '' Otocinclus hasemani'' Steindachner, 1915 * '' Otocinclus hoppei'' A. Miranda-Ribeiro, 1939 * '' Otocinclus huaorani''

, 1997 * '' Otocinclus juruenae'' A. C. Ribeiro & Lehmann A., 2016 Ribeiro, A.C. & Lehmann, A., P. (2016): A new ''Otocinclus'' (Siluriformes: Loricariidae: Hypoptopomatinae) from the Rio Juruena Basin, central Brazil. ''Zootaxa, 4147 (3): 240–246.'' * '' Otocinclus macrospilus'' C. H. Eigenmann & W. R. Allen, 1942 * '' Otocinclus mangaba'' Lehmann A., Mayer & R. E. dos Reis, 2010 Lehmann, A., P., Mayer, F. & Reis, R.E. (2010): A New Species of ''Otocinclus'' (Siluriformes: Loricariidae) from the Rio Madeira Drainage, Brazil. ''Copeia, 2010 (4): 635–639.'' * '' Otocinclus mariae'' Fowler, 1940 * '' Otocinclus mimulus'' Axenrot & S. O. Kullander, 2003 * '' Otocinclus mura''

, 1997 * '' Otocinclus tapirape'' M. R. Britto & C. L. R. Moreira, 2002 * '' Otocinclus vestitus''

, 1872 * '' Otocinclus vittatus''

, 1904 * '' Otocinclus xakriaba''

, 1997 '' Macrotocinclus affinus'' was considered to be a member of ''Otocinclus'' until it was moved to its own monotypic genus, '' Macrotocinclus''.''Macrotocinclus'' Isbrücker & Seidel, 2001 in GBIF Secretariat (2019). GBIF Backbone Taxonomy. Checklist dataset https://doi.org/10.15468/39omei accessed via GBIF.org on 2020-12-16. The name ''Otocinclus affinus'' is still used in the aquarium trade, however it actually refers to members of ''O. vittatus'', ''O. vestitus'' and ''O. macrospilus.''

Ecology

Species of this genus are diurnal and generally are found in small streams or along the margins of larger rivers, clinging to substrates using their

. The fish of this genus primarily feed on

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

or aufwuchs on roots, stones, macrophytes and broad-leaved grasses. They inhabit well-oxygenated, moderate- to slow-flowing environments, often near river banks. They are found near the surface of the water, but are often associated with vegetation or other structures. They lay adhesive

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

and do not guard them; this is in contrast to many other loricariids where the male builds a nest and guards the eggs. These fish live in shoals or schools. ''Otocinclus'' are able to breathe air. Prior to surfacing, they will release air through their gills and mouth. Upon returning to the bottom, the fish do not need to pump their buccal cavities, indicating they are absorbing oxygen from the swallowed air. ''O. flexilis'', ''O. mimulus'' and ''O. xakriaba'' are considered to be

Batesian mimic Batesian mimicry is a form of mimicry where a harmless species has evolved to imitate the warning signals of a harmful species directed at a predator of them both. It is named after the English naturalist Henry Walter Bates, after his work on bu ...

s of certain ''

Corydoras ''Corydoras'' is a genus of freshwater catfish in the family Callichthyidae and subfamily Corydoradinae. The species usually have more restricted areas of endemism than other callichthyids, but the area of distribution of the entire genus almost ...

'' species ('' C. diphyes'', '' C. garbei'', '' C. nattereri'' and '' C. paleatus'', respectively). These ''Corydoras'' species have bony plates of armor and strong spines as defenses, making them less palatable; by mimicking these species in size and coloration, ''Otocinclus'' spp. avoid predation.Axenrot, T.E. & Kullander, S.O. (2003)
''Corydoras diphyes'' (Siluriformes: Callichthyidae) and ''Otocinclus mimulus'' (Siluriformes: Loricariidae), two new species of catfishes from Paraguay, a case of mimetic association.
''Ichthyological Exploration of Freshwaters, 14 (3): 249–272.''

References

{{Taxonbar, from=Q1141986 Hypoptopomatini Fish of South America Catfish genera Taxa named by Edward Drinker Cope Freshwater fish genera