# Hypostomus

Hypostomus is a genus of catfish in the family Loricariidae. They are native to tropical and subtropical South America. H. plecostomus is the popular freshwater aquarium fish formerly known as Plecostomus plecostomus. The taxonomic structure of the Loricariidae is still being expanded by scientists. Hypostomus is a highly species-rich and widely distributed catfish genus.

## Taxonomy and phylogeny

This genus is the type member of its tribe Hypostomini and subfamily Hypostominae. The type species of Hypostomus is H. guacari.
With the inclusion of Aphanotorulus, Isorineloricaria and Squaliforma, the genus Hypostomus is by far the largest genus of Loricariidae and the second largest genus of catfish. However, a good way to split up the genus further is unclear. Species level taxonomy of Hypostomus is still poorly known as well as the phylogenetic relationships within and of the genus. It has been shown that the genus does not form a natural group. However, small monophyletic groups are known to exist within the genus Hypostomus, such as the H. cochliodon group. Aphanotorulus and Isorineloricaria are considered separate genera by some authors based on molecular information.
Studies conducted with representatives of some genera of Hypostominae showed that within this group, the diploid number ranges from 2n = 52 to 2n = 80. However, the supposed wide karyotypic diversity that the family Loricariidae or the subfamily Hypostominae would present is almost exclusively restricted to the genus Hypostomus and the species from the other genera had a conserved diploid number.

## Distribution and habitat

These species are originate from freshwater habitats of South America and the Caribbean island of Trinidad. They are found throughout most of the range of loricariids except for drainages west of the Atrato River (northwest Colombia). They are essentially ubiquitous throughout their range. Maximum diversity in number of species of Hypostomus occurs in rivers of the Paraná-Paraguay system.
Hypostomus species are found in almost all aquatic habitats, from large rivers to small rivulets. The typical habitat would be relatively fast moving water over a shallow gravel bed. Most species are lowland, sluggish stream- and lake-dwellers usually found associated with submerged wood; however, many species may be found among rocks in piedmont to mountain streams with moderate to swift flow. Members of this genus may be found over a range of substrates such mud, detritus, gravel, and sand. Many species spawn in hollows dug into mud banks or within hollow logs.

## Description and ecology

As in all loricariids, these species have a suckermouth. They use their mouth as well as the pectoral, pelvic and caudal fin areas, to interact with the rocky river-bottom. The comb-toothed inferior mouth of Hypostomus is able to grasp green algae on the river bottom. With the help of the suckermouth, which anchor the fishes, in conjunction with the arched design of pectoral and pelvic fin spines, they are also able to remain upright while exploring this substratum. In addition, their large, concave caudal fin is associated with fast locomotion over short distances.
Also like other loricariids, Hypostomus species exhibit plates of armor over their body. The colouration among Hypostomus species varies. They may have a white ground color and black spots, or brown and spotted, or even black with red, gold, or white spots. Abdomen also varies in color from white to black and may be spotted or not. The caudal fin is forked with the lower lobe longer than upper. Most species have stout bodies, but some do have thinner, elongate bodies.
In most species, males develop hypertrophied odontodes on the leading edge of the pectoral fin spine and the end of the spine may become swollen. In some species, the males may also develop hypertrophied odontodes on the body during the breeding season.
Hypostomus species are well known for the ability to breathe air. This is achieved through a slightly modified stomach that is larger and thinner than in non-air breathers. To breathe air, Hypostomus must orient itself vertically.
Species of the H. cochliodon group are fairly large loricariids that reach about 30 centimetres (12 in) SL. Their colouration is typically dark brown with spots generally developed over most surfaces; however, most species of this group have been observed to have a well-developed ability to alter color according to substrate. Except for H. sculpodon, these species tend to have a deep body at the dorsal fin origin; this makes the body appear humped. Along with Panaque, species of the H. cochliodon group are unique among loricariids for xylophagy, or the ability to digest wood, accomplished through specialized spoon-shaped teeth. In H. hemicochliodon and H. sculpodon appear to be intermediate between other species of Hypostomus and the H. cochilodon group by feeding less on wood and lacking specialized teeth; many other Hypostomus will occasionally eat wood, but wood only amounts to a very small fraction of their diet.

## Species

There are currently 156 recognized species in this genus:
| Hypostomus affinis (Steindachner, 1877) Hypostomus agna (A. Miranda-Ribeiro, 1907) Hypostomus alatus Castelnau, 1855 Hypostomus albopunctatus (Regan, 1908) Hypostomus ancistroides (R. von Ihering (pt), 1911) Hypostomus angipinnatus (Leege, 1922) Hypostomus annectens (Regan, 1904) Hypostomus arecuta Y. P. Cardoso, Almirón, Casciotta, Aichino, Lizarralde & Montoya-Burgos, 2012 Hypostomus argus (Fowler, 1943) Hypostomus asperatus Castelnau, 1855 Hypostomus aspidolepis (Günther, 1867) Hypostomus aspilogaster (Cope, 1894) Hypostomus atropinnis (C. H. Eigenmann & R. S. Eigenmann, 1890) Hypostomus auroguttatus Kner, 1854 Hypostomus basilisko Tencatt, Zawadzki & Froehlich, 2014 Hypostomus bolivianus (N. E. Pearson, 1924) Hypostomus borellii (Boulenger, 1897) Hypostomus boulengeri (C. H. Eigenmann & C. H. Kennedy, 1903) Hypostomus brevicauda (Günther, 1864) Hypostomus brevis (Nichols, 1919) Hypostomus careopinnatus Martins, Marinho, Langeani & J. P. Serra, 2012 Hypostomus carinatus (Steindachner, 1881) Hypostomus carvalhoi (A. Miranda-Ribeiro, 1937) Hypostomus chrysostiktos Birindelli, Zanata & F. C. T. Lima, 2007 Hypostomus cochliodon Kner, 1854 Hypostomus commersoni Valenciennes, 1836 Hypostomus coppenamensis Boeseman, 1969 Hypostomus corantijni Boeseman, 1968 Hypostomus cordovae (Günther, 1880) Hypostomus crassicauda Boeseman, 1968 Hypostomus dardanelos Zawadzki & P. H. Carvalho, 2014 Hypostomus delimai Zawadzki, R. R. de Oliveira & Debona, 2013 Hypostomus denticulatus Zawadzki, C. Weber & Pavanelli, 2008 Hypostomus derbyi (Haseman, 1911) Hypostomus dlouhyi C. Weber, 1985 Hypostomus eptingi (Fowler, 1941) Hypostomus ericae P. H. Carvalho & C. Weber, 2005 Hypostomus ericius Armbruster, 2003 Hypostomus faveolus Zawadzki, Birindelli & F. C. T. Lima, 2008 Hypostomus fluviatilis (Schubart, 1964) Hypostomus fonchii C. Weber & Montoya-Burgos, 2002 Hypostomus formosae Y. P. Cardoso, Brancolini, Paracampo, Lizarralde, Covain & Montoya-Burgos, 2016 Hypostomus francisci (Lütken, 1874) Hypostomus garmani (Regan, 1904) Hypostomus goyazensis (Regan, 1908) Hypostomus gymnorhynchus (Norman, 1926) Hypostomus hemicochliodon Armbruster, 2003 Hypostomus hemiurus (C. H. Eigenmann, 1912) Hypostomus heraldoi Zawadzki, C. Weber & Pavanelli, 2008 Hypostomus hermanni (R. Ihering (pt), 1905) Hypostomus holostictus (Regan, 1913) Hypostomus hondae (Regan, 1912) Hypostomus hoplonites Rapp Py-Daniel, 1988 Hypostomus iheringii (Regan, 1908) Hypostomus interruptus (A. Miranda-Ribeiro, 1918) Hypostomus isbrueckeri R. E. dos Reis, C. Weber & L. R. Malabarba, 1990 Hypostomus itacua Valenciennes, 1836 Hypostomus jaguar Zanata, Sardeiro & Zawadzki, 2013 Hypostomus jaguribensis (Fowler, 1915) Hypostomus johnii (Steindachner, 1877) Hypostomus khimaera Tencatt, Zawadzki & Froehlich, 2014 Hypostomus kopeyaka P. H. Carvalho, F. C. T. Lima & Zawadzki, 2010 Hypostomus kuarup Zawadzki, Birindelli & F. C. T. Lima, 2012 Hypostomus lamberti Penido, Pessali & Zawadzki, 2023 Hypostomus laplatae (C. H. Eigenmann, 1907) Hypostomus latifrons C. Weber, 1986 Hypostomus latirostris (Regan, 1904) Hypostomus leucophaeus Zanata & Pitanga, 2016 Hypostomus levis (N. E. Pearson, 1924) Hypostomus lexi (R. Ihering (pt), 1911) Hypostomus lima (Lütken, 1874) Hypostomus longiradiatus (Holly, 1929) Hypostomus luetkeni (Steindachner, 1877) Hypostomus luteomaculatus (Devincenzi, 1942) Hypostomus luteus (Godoy (pt), 1980) Hypostomus macrophthalmus Boeseman, 1968 Hypostomus macrops (C. H. Eigenmann & R. S. Eigenmann, 1888) Hypostomus macushi Armbruster & L. S. Souza, 2005 Hypostomus maracaiboensis (L. P. Schultz, 1944) Hypostomus margaritifer (Regan, 1908) | Hypostomus melanephelis Zawadzki, A. S. Oliveira, R. R. de Oliveira & Rapp Py-Daniel, 2015 Hypostomus meleagris (Marini, Nichols & La Monte, 1933) Hypostomus micromaculatus Boeseman, 1968 Hypostomus microstomus C. Weber, 1987 Hypostomus multidens Jerep, Shibatta & Zawadzki, 2007 Hypostomus mutucae Knaack, 1999 Hypostomus myersi (Gosline, 1947) Hypostomus nematopterus Isbrücker & Nijssen, 1984 Hypostomus niceforoi (Fowler, 1943) Hypostomus nickeriensis Boeseman, 1969 Hypostomus niger (Marini, Nichols & La Monte, 1933) Hypostomus nigromaculatus (Schubart, 1964) Hypostomus nigropunctatus Garavello, Britski & Zawadzki, 2012 Hypostomus nudiventris (Fowler, 1941) Hypostomus obtusirostris (Steindachner, 1907) Hypostomus occidentalis Boeseman, 1968 Hypostomus oculeus (Fowler, 1943) Hypostomus pagei Armbruster, 2003 Hypostomus pantherinus Kner, 1854 Hypostomus papariae (Fowler, 1941) Hypostomus paranensis Weyenbergh (de), 1877 Hypostomus paucimaculatus Boeseman, 1968 Hypostomus paucipunctatus P. H. Carvalho & C. Weber, 2005 Hypostomus paulinus (R. Ihering (pt), 1905) Hypostomus peckoltoides Zawadzki, C. Weber & Pavanelli, 2010 Hypostomus perdido Zawadzki, Tencatt & Froehlich, 2014 Hypostomus piratatu C. Weber, 1986 Hypostomus plecostomoides (C. H. Eigenmann, 1922) Hypostomus plecostomus (Linnaeus, 1758) (sucker-mouth catfish) Hypostomus pospisili (L. P. Schultz, 1944) Hypostomus pseudohemiurus Boeseman, 1968 Hypostomus punctatus Valenciennes, 1840 Hypostomus pusarum (Starks, 1913) Hypostomus pyrineusi (A. Miranda-Ribeiro, 1920) Hypostomus regani (Ihering, 1905) Hypostomus renestoi Zawadzki, da Silva & Troy, 2018 Hypostomus rhantos Armbruster, Tansey & Lujan, 2007 Hypostomus robinii Valenciennes, 1840 Hypostomus rondoni (A. Miranda-Ribeiro, 1912) Hypostomus roseopunctatus R. E. dos Reis, C. Weber & L. R. Malabarba, 1990 Hypostomus salgadae (Fowler, 1941) Hypostomus saramaccensis Boeseman, 1968 Hypostomus scabriceps (C. H. Eigenmann & R. S. Eigenmann, 1888) Hypostomus scaphyceps (Nichols, 1919) Hypostomus sculpodon Armbruster, 2003 Hypostomus seminudus (C. H. Eigenmann & R. S. Eigenmann, 1888) Hypostomus sertanejo Zawadzki, Ramos & Sabaj, 2017 Hypostomus simios P. H. Carvalho & C. Weber, 2005 Hypostomus sipaliwinii Boeseman, 1968 Hypostomus soniae P. H. Carvalho & C. Weber, 2005 Hypostomus spiniger (Hensel, 1870) Hypostomus strigaticeps (Regan, 1908) Hypostomus subcarinatus Castelnau, 1855 Hypostomus surinamensis Boeseman, 1968 Hypostomus tapanahoniensis Boeseman, 1969 Hypostomus taphorni (Lilyestrom, 1984) Hypostomus tapijara Oyakawa, Akama & Zanata, 2005 Hypostomus tenuis Boeseman, 1968 Hypostomus ternetzi (Boulenger, 1895) Hypostomus tietensis (R. Ihering (pt), 1905) Hypostomus topavae (Godoy (pt), 1969) Hypostomus unae (Steindachner, 1878) Hypostomus uruguayensis R. E. dos Reis, C. Weber & L. R. Malabarba, 1990 Hypostomus vaillanti (Steindachner, 1877) Hypostomus variipictus (R. Ihering (pt), 1911) Hypostomus varimaculosus (Fowler, 1945) Hypostomus variostictus (A. Miranda-Ribeiro, 1912) Hypostomus ventromaculatus Boeseman, 1968 Hypostomus vermicularis (C. H. Eigenmann & R. S. Eigenmann, 1888) Hypostomus waiampi P. H. Carvalho & C. Weber, 2005 Hypostomus watwata Hancock, 1828 (armored catfish) Hypostomus weberi P. H. Carvalho, F. C. T. Lima & Zawadzki, 2010 Hypostomus wilsoni (C. H. Eigenmann, 1918) Hypostomus winzi (Fowler, 1945) Hypostomus wuchereri (Günther, 1864) Hypostomus yaku Martins, Langeani & Zawadzki, 2014 Hypostomus cari Lustosa-Costa, Ramos, Zawadzki, Jacobina & Lima, 2024 |