Hypostomini Kner, 1853

Tribe Hypostomini Kner, 1853

Included genera.

‘ Hemiancistrus ’ chlorostictus group (Armbruster et al., 2015).

Hypostomus Lacépède, 1803:144 . Type-species: Hypostomus guacari Lacépède, 1803 . Synonyms: Cheiridodus Eigenmann, 1922 , Cochliodon Heckel, 1854 (in Kner, 1854), Plecostomus Gronow 1763 , and Watawata Isbrücker & Michels, 2001 (in Isbrücker et al., 2001).

Pterygoplichthys Gill, 1858:408 . Type-species: Hypostomus duodecimalis Valenciennes, 1840 (in Cuvier, Valenciennes, 1840). Synonyms: Glyptoperichthys Weber, 1991 and Liposarcus Günther, 1864 .

Phylogenetic diagnosis. No unambiguous character states were found to support

Hypostomini .

Comparative diagnosis. Hypostomini contains most of the large, stout-bodied loricariids, but these can be difficult to distinguish from other Hypostominae except by genus or species group. Hypostomus (with the exception of H. cerrado ) differs from all other Hypostomini as well as all other tribes (except Corymbophanes of the Ancistrini , Aphanotorulus , Isorineloricaria , and Peckoltia relictum of the Peckoltini , and Spectracanthicus murinus of the Spectracanthicini ) by having the cheek plates evertible to only about 30° from the head and lacking hypertrophied odontodes (vs. 75°+ from the head and having hypertrophied odontodes; Pseudancistrus have hypertrophied cheek odontodes, but cannot evert their cheek odontodes beyond 30°); from Corymbophanes by having either an adipose fin or fin completely missing without replacement by azygous plates (vs. adipose fin replaced by postdorsal ridge of raised azygous plates) and by having an iris operculum (vs. iris operculum absent); from Aphanotorulus and Isorineloricaria by lacking hypertrophied odontodes on the lateral trunk plates of nuptial males (vs. lateral plates and/or caudal-fin spines covered in large odontodes in nuptial males), by generally being brown with black spots or saddles or dark gray with light spots ( Hypostomus yaku is uniformly brown, Martins et al., 2014) (vs. almost white to light tan with black spots); and by having a small buccal papilla (vs. single large or many small buccal papillae); from Peckoltia relictum by completely lacking hypertrophied cheek odontodes (vs. very small cheek odontodes); and from S. murinus by having dorsal fin free from adipose (vs. posterior membrane of dorsal fin expanded, entirely adnate to body reaching adipose-fin spine).

Pterygoplicthys can be separated from all other Hypostominae except Acanthicini , Chaetostomatini , and Colossimystax by having nine to 14 dorsal-fin rays (vs. seven); from Acanthicini by having relatively weak lateral plate keels and associated odontodes (vs. strong/sharp), by having odontodes evenly distributed across lateral plates (vs. odontodes reduced above and below keel rows), and by having a weaker ability to evert cheek-odontodes; and from Chaetostomatini and Colossimystax by having elongate lateral plate keels (vs. keels absent or with rounded clusters of odontodes in Andeancistrus platycephalus and Chaetostoma spondylus Salcedo & Ortega, 2015 ) and by having plates on the abdomen (vs. plates absent). Hypostomus cerrado and the ‘ Hemiancistrus ’ chlorostictos group have evertible cheek plates with hypertrophied odontodes.

Hypostomus cerrado can be separated from most other Hypostominae tribes by having weak lateral plate keels and a distally expanded pectoral-fin spine forming a club-like structure in adults (vs. no lateral plate keels in most other tribes or very strong keels and associated odontodes in Acanthicini and no expansion of the pectoral-fin spine). The ‘ Hemiancistrus ’ chlorostictos group can be separated from Ancistrus , Araichthys , Corymbophanes , Dekeyseria , Lasiancistrus , Neblinichthys , and Pseudolithoxus by having five rows of plates on the caudal peduncle (vs. three); from Ancistomus by either being almost black with white spots or tan with black spots (vs. gray with black spots); from Aphanotorulus and Isorineloricaria by either being almost black with white spots or tan with medium black spots (vs. very light gray or tan with small black spots), by nuptial males lacking hypertrophied odontodes on lateral plates (vs. nuptial males with hypertrophied odontodes dense and widespread on lateral plates, especially caudally), from Aphanotorulus by having a small buccal papilla (vs. buccal papilla large or numerous and widespread); from Baryancistrus , ‘ Baryancistrus ’, Parancistrus , and Spectracanthicus , by having a small posterior membrane of the dorsal fin (vs. posterior membrane of dorsal fin expanded, reaching the adipose-fin spine in all except B. longipinnis ); from Panafilus, Panaqolus , Panaque , many Peckoltia , Peckoltichthys , Pseudoqolus , and Scobinancistrus by having dentaries long and forming an oblique angle with many small teeth (vs. dentaries short and forming an acute angle with fewer, larger teeth) and from remaining Peckoltia by being either almost black with white spots or tan with large black spots (vs. with dorsal saddles, with very large dark spots, being almost colorless, or having a golden tan background color with no spots); from ‘ B.’ demantoides , ‘ H. ’ guahiborum , and ‘ H.’ subviridis by lacking a light edge to the dorsal and/or caudal fins (vs. yellow or orange bands along edges of dorsal and/or caudal fins).

Geographical distribution. Hypostomini is broadly distributed across cis-Andean South American drainages from the La Plata River northward (including Trinidad), and trans-Andean drainages from northern Ecuador to the Terraba River of Costa Rica (extending further into Central America than any other loricariid lineage). Introduced populations of mainly Pterygoplichthys but also Hypostomus are found in tropical and subtropical regions around the world.