''Homodiaetus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

pencil catfish Trichomycteridae is a family of catfishes commonly known as pencil catfishes or parasitic catfishes. This family includes the candiru fish (''Vandellia cirrhosa''), feared by some people for its alleged habit of entering into the urethra of hum ...

es native to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

Species

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

Homodiaetus anisitsi ''Homodiaetus'' is a genus of pencil catfishes native to South America. Species There are currently four recognized species in this genus: * '' Homodiaetus anisitsi'' Eigenmann & Ward, 1907 * '' Homodiaetus banguela'' Koch, 2002 * '' Homodiaetus ...

Eigenmann Eigenmann () is a surname. Notable persons with that surname include: * Andi Eigenmann (born 1990), Filipino actress * Carl H. Eigenmann (1863–1927), German–American ichthyologist, husband of Rosa Eigenmann * Eduardo de Mesa Eigenmann, birth n ...

Ward Ward may refer to: Division or unit * Hospital ward, a hospital division, floor, or room set aside for a particular class or group of patients, for example the psychiatric ward * Prison ward, a division of a penal institution such as a pris ...

, 1907 * '' Homodiaetus banguela''

Koch Koch may refer to: People * Koch (surname), people with this surname * Koch dynasty, a dynasty in Assam and Bengal, north east India * Koch family * Koch people (or Koche), an ethnic group originally from the ancient Koch kingdom in north east In ...

, 2002 * '' Homodiaetus graciosa''

, 2002 * ''

Homodiaetus passarellii ''Homodiaetus'' is a genus of pencil catfishes native to South America. Species There are currently four recognized species in this genus: * ''Homodiaetus anisitsi'' Eigenmann & Ward, 1907 * '' Homodiaetus banguela'' Koch, 2002 * '' Homodiaetus ...

'' ( Miranda-Ribeiro, 1944)

Distribution

The distribution of ''Homodiaetus'' is restricted to the southeastern

, from

Uruguay Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the A ...

Paraguay River The Paraguay River (''Ysyry Paraguái'' in Guarani language, Guarani, ''Rio Paraguai'' in Portuguese language, Portuguese, ''Río Paraguay'' in Spanish language, Spanish) is a major river in south-central South America, running through Brazil, Bol ...

s in the west to the coastal drainages of the

Rio de Janeiro State Rio de Janeiro () is one of the 27 federative units of Brazil. It has the second largest economy of Brazil, with the largest being that of the state of São Paulo. The state, which has 8.2% of the Brazilian population, is responsible for 9.2% of ...

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. ''H. anisitsi'' originates from the

Paraná Paraná, Paranã or Parana may refer to: Geology * Paraná Basin, a sedimentary basin in South America Places In Argentina *Paraná, Entre Ríos, a city * Paraná Department, a part of Entre Ríos Province In Brazil *Paraná (state), a state ...

-Paraguay River basin. ''H. banguela'' inhabits the São João River and ''H. passarellii'' is known from coastal basins in the State of Rio de Janeiro. ''H. graciosa'' is distributed in coastal basins of southeastern Brazil in states of

and

São Paulo São Paulo (; ; Portuguese for 'Paul the Apostle, Saint Paul') is the capital of the São Paulo (state), state of São Paulo, as well as the List of cities in Brazil by population, most populous city in Brazil, the List of largest cities in the ...

Description

''Homodiaetus'' is currently distinguished from other genera of

Stegophilinae The Stegophilinae are a subfamily of catfishes (order Siluriformes) of the family Trichomycteridae. It includes 12 genera: '' Acanthopoma'', '' Apomatoceros'', '' Haemomaster'', '' Henonemus'', '' Homodiaetus'', '' Megalocentor'', '' Ochmacanthu ...

by the combination of the origin of the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

midlength between the tip of the snout and the caudal-fin origin, 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 ...

with three or more

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 t ...

s, and the

gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

membranes confluent with the

isthmus An isthmus (; : isthmuses or isthmi) is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea count ...

. ''Homodiaetus'' species are small and grow up to 42 millimetres (1.7 in) SL. They are transparent with the except of the head and abdomen. ''Homodiaetus'' species have a thin body and depressed head that is almost as wide as the head is long. The dorsal and ventral profiles are straight except for a

convex Convex or convexity may refer to: Science and technology * Convex lens, in optics Mathematics * Convex set, containing the whole line segment that joins points ** Convex polygon, a polygon which encloses a convex set of points ** Convex polytop ...

head. The mouth is inferior. ''H. anisitsi'' has three dark bands on its caudal fin, while dark lines are irregular or absent in the other three species. Among the other three species, ''H. graciosa'' has 5–6 rows of teeth in the

dentary In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...

(vs. 6–7 in the other two species). ''H. graciosa'' has 7–9 (usually 8) opercular

s, ''H. passarellii'' has 6–7, and ''H. banguella'' has 9.

Ecology

''Homodiaetus'' species are found in

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') an ...

s and arenaceous rivers of little depth. These fish are known to be lepidophagous, meaning they feed upon scales.

References

{{Taxonbar, from=Q5891083 Trichomycteridae Catfish of South America Freshwater fish genera Catfish genera Taxa named by Carl H. Eigenmann