''Typhlobelus'' 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 ...

of pencil catfishes 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 ...

Species

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

Typhlobelus auriculatus ''Typhlobelus'' is a genus of pencil catfishes native to South America. Species There are currently five recognized species in this genus: * '' Typhlobelus auriculatus'' de Pinna & Zuanon, 2013de Pinna, M.C.C. & Zuanon, J. (2013): The Genus ' ...

'' de Pinna & Zuanon, 2013de Pinna, M.C.C. & Zuanon, J. (2013): The Genus ''Typhlobelus'': Monophyly and Taxonomy, with Description of a New Species with a Unique Pseudotympanic Structure (Teleostei: Trichomycteridae). ''Copeia, 2013 (3): 441-453.'' * '' Typhlobelus guacamaya'' Schaefer, Provenzano, de Pinna & Baskin, 2005 * ''

Typhlobelus lundbergi ''Typhlobelus'' is a genus of pencil catfishes native to South America. Species There are currently five recognized species in this genus: * '' Typhlobelus auriculatus'' de Pinna & Zuanon, 2013de Pinna, M.C.C. & Zuanon, J. (2013): The Genus ' ...

'' Schaefer, Provenzano, de Pinna & Baskin, 2005 * '' Typhlobelus macromycterus'' Costa & Bockmann, 1994 * '' Typhlobelus ternetzi''

Myers Myers as a surname has several possible origins, e.g. Old French ("physician"), Old English ("mayor"), and Old Norse ("marsh"). People *Abram F. Myers (born 1889), chair of the Federal Trade Commission and later general counsel and board chai ...

, 1944

Distribution

''T. guacamaya'' originates from the

Cuao River Cuao River is a river of Venezuela. It is part of the Orinoco River basin. See also *List of rivers of Venezuela This is a list of rivers in Venezuela. By drainage basin This list is arranged by drainage basin, with respective tributaries inden ...

in the

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...

River basin of

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 ...

. ''T. lundbergi'' inhabits the lower Orinoco River, between

Ciudad Bolivar Ciudad () is the Spanish word for City Ciudad may also refer to: *La Ciudad (archaeological site), Hohokam ruins in Phoenix, Arizona *La Ciudad, district of Durango City, Mexico *''La ciudad'', novel by Mario Levrero 1970 *La Ciudad ''The City'' ...

and Los Castillos de Guayana (near

Ciudad Guayana Ciudad Guayana () (in English Guayana City) is a city in Bolívar State (Venezuela), Bolívar State, Venezuela. It stretches 40 kilometers along the south bank of the Orinoco, Orinoco river, at the point where it is joined by its main tributary ...

), Venezuela. ''T. macromycterus'' is known from the

Tocantins River The Tocantins River ( pt, Rio Tocantins, link=no , , Parkatêjê dialect, Parkatêjê: ''Pyti'' ɨˈti is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" (''Tukã'' for "toucan ...

near Tucuruí,

Pará State Pará is a state of Brazil, located in northern Brazil and traversed by the lower Amazon River. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest are the borders of Guyana and Sur ...

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 ...

. ''T. ternetzi'' lives in the upper Rio Negro basin, Brazil.

Description

Species of ''Typhlobelus'' share the extreme reduction of pigmentation, loss of the

dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through conv ...

, the loss or extreme reduction of

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, a reduced

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...

, and the reduction or complete loss of eyes in some species. These fish are markedly miniaturized, yet retain a relatively well-ossified skeleton comparable in both bone differentiation and degree of calcification to that observed in larger trichomycterids. ''T. guacamaya'' is distinguished from all congeners by the presence of three

branchiostegal rays This glossary of ichthyology is a list of definitions of terms and concepts used in ichthyology, the study of fishes. A B C ...

(vs. four in ''T. ternetzi'' and ''T. lundbergi'', five in ''T. macromycterus''), posterior

naris A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

absent (vs. present, nares bilaterally paired), and the lack of

pleural rib The pleural cavity, pleural space, or interpleural space is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication b ...

s (vs. one pair of pleural ribs associated with the first free vertebra). ''T. lundbergi'' is distinguished from all congeners by the presence of four laterosensory pores on the head (vs. three). Both ''T. guacamaya'' and ''T. lundbergi'' are distinguished from '' ternetzi'' and ''T. macromycterus'' by the absence of eyes (vs. eyes present and

vestigial Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...

); between ''T. ternetzi'' and ''T. lundbergi'', the distinction may be between the presence or absence of eyes or eyespots. ''T. macromycterus'' has one or two odontodes on the

opercle The operculum is a series of bones found in bony fish and chimaeras that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. Anatomy The opercular series contains four bon ...

and five branchiostegal rays, while ''T. ternetzi'' and ''T. lundbergi'' have no odontodes and four branchiostegal rays. These fish have greatly elongate, slender bodies. These fish have three pairs of barbels, all similar in length and general appearance. The mouth is ventral. ''Typhlobelus'' has a long duck-billed rostrum that protrudes anteriorly well beyond the bases of the maxillary barbels.

References

{{Taxonbar, from=Q7861016 Trichomycteridae Fish of South America Fish of Brazil Fish of Venezuela Freshwater fish genera Catfish genera Taxa named by George S. Myers